Think Bigger, Act Larger: A U.S.-Australia Led Coalition for a Combined Joint Deterrence Force in the Indo-Pacific

Alliance Future: Rewiring Australia and the United States

The Carnegie Asia Program’s “Alliance Future” project aims to ensure that Canberra and Washington are working to operationalize and integrate their alliance in new ways. The project explores how to undertake difficult reforms, forge new modes of cooperation, harmonize outdated regulations, better align national strategies, address sovereignty concerns and risk thresholds, and ultimately reform the alliance for a more competitive era.

Introduction

The United States, Australia, Japan, and other like-minded allies and partners need to think bigger and more ambitiously to ensure that the Indo-Pacific remains free, open, prosperous, and secure. Threats to regional security by China are undercutting the rules-based order. No singular nation, alliance, or existing multilateral forum can effectively deter the types of actions and tactics China utilizes to undermine international law in pursuit of its strategic ambitions. The region’s evolving security architecture, marked by a so-called latticework of burgeoning minilateral and bilateral partnerships, reflects a growing desire for collective approaches. Yet, this diffuse framework lacks the structural coherence required to fully integrate disparate components into a cohesive, coordinated, and integrated combined deterrence force. Like-minded nations must urgently establish a framework that consolidates their collective capabilities to deter shared threats and respond if deterrence fails, while competing for mutual interests to secure a free and open Indo-Pacific.

The establishment of a combined Joint Deterrence Force (JDF) in the Indo-Pacific is an opportunity to fill a critical gap in the security architecture. By capitalizing on the current political synergies among the United States, Australia, and Japan these nations must take steps to better integrate their combined capabilities and capacities for more effective deterrence. This paper describes how a JDF, led by the United States and supported by existing collective deterrence cooperation with allies like Australia and Japan, would serve as the bedrock of a deterrence coalition. Further, it explores the dynamic and evolving security architecture that is giving way to ambitious collaboration but lacks a common strategic framework and a mechanism to actualize the force-multiplying power of an operationalized deterrence coalition. Finally, two existing multinational forces, the UK-led Joint Expeditionary Forces and the U.S.-led Combined Maritime Forces, are reviewed to derive lessons and inform the features of a JDF.

An Evolving Indo-Pacific Security Architecture

The Indo-Pacific region is undergoing a profound transformation. The move from unipolarity to multipolarity is marked by a growing preference among nations from formal alliances to more flexible arrangements, and from multilateralism to minilateralism, giving rise to coalitions.¹ A range of tectonic geopolitical shifts are behind these changes: the loss of America’s regional primacy; China’s increasingly coercive military actions and aggressive sovereignty claims; the rise of new and emerging players like India; and the global ripple effect of Russia’s invasion of Ukraine. Heightened insecurity caused by this broad dynamic is resulting in more nations seeking new or deeper defense cooperative relationships to reinforce their collective ability to respond to threats to their interests. As China grows more assertive—through actions that jeopardize regional peace, stability, and prosperity—nations are increasingly investing in minilateral coalitions. The impetus is not only for their own national security, but the acknowledgment that their peace, stability, and prosperity won’t mean much without the collective security of the region.

A main driver behind the region’s evolving security order is the combination of China’s explicitly stated ambition to establish “world-class forces by the mid-21st century” to ensure its “territorial sovereignty, maritime rights and interests, and national unity.”² China’s opaque military and nuclear modernization is happening at a pace and scale not seen in the world for half a century, and is underscored by sustained defense budget investments—in 2024 China spent $236 billion, representing just 1.3 percent of its gross domestic product (GDP).³ The Chinese army and navy (and shipbuilding industry) are the largest in the world, its aviation force is the largest in the region, and it continues to upgrade its strategic forces to include intermediate-range ballistic missiles equipped with hypersonic glide vehicles capable of evading missile defenses.⁴

China’s military expansion enables its pursuit of greater power projection capabilities, positioning itself as a formidable force both within and beyond the region. Beijing is increasingly wielding its military power in ways that harass, intimidate, or test the resolve of its neighbors by gradually shifting the status quo without shattering the glass plate that would potentially trigger a military response. The June 2024 South China Sea maritime confrontation with the Philippines over the Second Thomas Shoal epitomizes the type of hybrid tactics China employs to advance disputed territorial claims along the first island chain that are escalating regional tensions.

China’s aggressive pursuit of its strategic ambitions directly challenges U.S. dominance, which no longer holds uncontested sway as the regional hegemon. Beijing’s revisionist policies are in contravention of international principles of sovereignty, territorial integrity, and freedom of navigation, all fundamental to a free and open Indo-Pacific. This is not merely a bilateral contest, but a more complex, multifaceted competition, where shifting geopolitical dynamics and interdependencies are drawing in a broader array of actors.⁵

The Rise of Collective Deterrence Through Minilateralism

Recognizing that no single nation or bilateral alliance can unilaterally advance its own interests, America along with its allies and partners are increasingly diversifying and deepening security arrangements toward a shared vision of a free and open Indo-Pacific. The rise of minilateralism has advanced both U.S. objectives and collective regional aims by reinforcing the pillars of effective deterrence: capability, credibility, and communication. America’s focus on great power competition has renewed its emphasis on working closely with allies and partners to address shortfalls in power projection and enhance deterrence to maintain the status quo, as well as dissuade the use of force to resolve disputes.⁶

America’s treaty alliances remain the backbone of its defense strategy in the Indo-Pacific. These alliances can enable the collective ability to address the challenges that China presents through a concept of integrated deterrence. The 2024 Commission on the National Defense Strategy highlighted significant ongoing gaps in the U.S. military’s capabilities and capacity to effectively deter or prevail in conflict.⁷ It also warns that the Joint Force is nearing a critical point in its ability to maintain readiness. The 2022 National Defense Strategy (NDS) had sought to reverse the trend of strategic overreach by placing allies and partners at the center of its integrated deterrence framework. This concept emphasizes combining strengths across warfighting domains, theaters, and the broader whole-of-government, as an all-hands-on-deck application of national power. 

Through the NDS, the U.S. Department of Defense was directed to strengthen and sustain deterrence by prioritizing interoperability and enabling coalitions with enhanced capabilities, new operating concepts, and combined, collaborative force planning.⁸ Central to the pursuit of integrated deterrence is the enhancement of and interoperability among ally and partner denial capabilities. U.S. allies and partners provide critical access and positioning, allowing routine military presence and operations near potential flashpoints such as Taiwan, enabling more timely U.S. responses to regional contingencies. Furthermore, a dispersed U.S. military presence across regional locations creates operational dilemmas for Beijing, forcing it to consider a coalition response in the event of an attack.

Collaborative efforts among the United States and its Indo-Pacific allies are increasingly focused on measures that support posture enhancements, defense industrial cooperation, technology transfers, and joint military exercises that are both supporting allied capacity to respond to regional contingencies and advance America’s integrated deterrence aims.⁹ New minilateral groupings, such as AUKUS (Australia, the United Kingdom, and the United States), exemplify this cooperation, with recent additional partnerships like the U.S.-Japan-Philippines Trilateral Agreement, the Australia-Japan-Philippines-U.S. Defense Ministers’ Meeting, and the signing of the U.S.-South Korea-Japan Trilateral Security Cooperation Framework, some of the notable examples of the level of momentum behind these burgeoning arrangements.

The expanding security architecture is evolving into a complex web: a latticework of minilateral groups layered over existing bilateral and multilateral relationships.¹⁰ According to the U.S. National Security Council senior director for East Asia and Oceania, the evolving latticework underpins the 2022 NDS by encouraging allies “to step up alongside the United States in new and innovative ways.”¹¹ No two nations share America’s commitment to advancing Indo-Pacific security through deterrence better than Australia and Japan. Both nations prioritize regional stability by countering China’s growing influence while ensuring a free and open Indo-Pacific. Their alignment is reflected in substantial commitments to increase national security–related spending, and a shared ambition to enhance their defense posture. This partnership is producing tangible results through reinforced security cooperation with the United States and building broader collaborations with other like-minded nations in the region. A closer analysis of both nations illuminates their distinct, yet convergent, perspectives on achieving a shared vision of a free and open Indo-Pacific through collective deterrence. This insight offers an essential context for understanding the challenges and opportunities they face in this evolving regional landscape and how more must be done to capitalize on this cooperation.

Japan’s Strategic Evolution: A Proactive Approach to Indo-Pacific Security

Over the last decade, Japan has made increasingly significant investments in defense capabilities and shifted toward a more proactive role in upholding regional security. China’s assertiveness and constant maritime pressure around the Senkaku Islands, the Russian invasion of Ukraine, and Beijing’s strategic alignment with Moscow, have driven Japan to reassess its strategic alignments, defense posture, and capabilities. Prime Minister Kishida Fumio’s remark, “Ukraine today may be East Asia tomorrow,” encapsulates Japanese national concern that a similar conflict is on its doorstep, prompting a focus on shaping and deterring for collective regional security.¹² Japan’s 2022 National Security Strategy, National Defense Strategy, and Defense Buildup Program (DBP) chart a strategic course that emphasizes strengthening its own defense and joint deterrence capabilities while deepening ties with the United States and other like-minded partners.¹³ Japan’s investments in long-range strike capabilities, new naval assets, self-destruct drones, a new satellite constellation, and advanced fighter jets reflect its commitment to a stronger deterrence posture. Japan’s ambitious plans represent its largest military buildup in postwar history¹⁴—funding its national strategies at a cost of approximately $319 billion over five years.¹⁵

Strategic defense investments serve to bolster Japan’s defense posture while reinforcing the joint deterrence capabilities with the United States. Central to Japan’s security strategy is the integration of its military assets with those of the United States, with the overarching objective of deterring any attempts to alter the regional status quo through force. These measures build upon nearly fifteen years of cooperation through the U.S.-Japan Extended Deterrence Dialogue. The venue has served as a critical coordination mechanism to establish a shared deterrence lexicon and policy framework, prioritize the alliance’s deterrence posture and response capabilities, and manage existing and emerging threats through the establishment of an Alliance Coordination Mechanism.¹⁶

Recently, the focus of Japan-U.S. alliance deterrence efforts is on deepening the integration of their military forces, thereby enhancing the credibility and effectiveness of their collective defense posture. Significant military investments have been directed toward improving coordination in intelligence, surveillance, and reconnaissance; optimizing the operational use of Japan’s counterstrike capabilities; and bolstering Japan’s support for the stationing of U.S. forces.¹⁷ This includes the forward deployment of a carrier strike group and the Third Marine Expeditionary Force, both of which are integral to U.S. power projection in East Asia and boosts the alliance’s combined deterrence and response capabilities.¹⁸ To enhance the alliance’s capacity to deter, joint flexible deterrent options and operational coordination functions, bilateral contingency planning, and additional training and exercises are being pursued in this era of strategic competition.¹⁹

In July 2024, the Japan-U.S. alliance announced its most far-reaching enhancements around coordination and command and control to strengthen the credibility of their deterrence posture in recognition of rising regional tensions. In a landmark decision, both nations agreed to pursue efforts that would reconstitute U.S. Forces Japan (USFJ) as a joint force headquarters (JFHQ) reporting to the Commander of U.S. Indo-Pacific Command (USINDOPACOM).²⁰ Through this approach, USFJ would augment its capabilities and operational cooperation with the Japan Self-Defense Forces Joint Operations Command (JJOC), and assume primary responsibility for coordinating security activities in and around Japan, in accordance with the U.S.-Japan Treaty of Mutual Cooperation and Security.²¹

Through a joint force headquarters, these allies’ forces improve their ability to respond rapidly and effectively to security threats, reinforcing the perception that they are unified and capable of countering aggression. This integration enhances deterrence in two key ways. First, the establishment of a JFHQ strengthens operational readiness, improving real-time situational awareness and the ability to make coordinated decisions swiftly. Second, by linking these command structures directly to USINDOPACOM, Japan and the United States demonstrate a robust, joint commitment to regional security, signaling to potential adversaries, such as China or North Korea, that any aggressive actions will be met with a highly coordinated and immediate response. This elevated coordination raises the cost of any military escalation for adversaries, enhancing the overall deterrent effect by demonstrating that Japan and the United States can credibly and decisively respond to threats.

Second only to Japan’s alliance with the United States is Japan’s robust and ambitious partnership with Australia. The relationship is rooted in shared values, a common strategic vision, mutual recognition of shared threats, shared status as middle powers, and close American allies. The 2022 Joint Declaration on Security Cooperation (JDSC), reaffirmed these nations’ Special Strategic Partnership, solidifying their collaborative commitment to maintaining a free and open Indo-Pacific, anchored in the rules-based international order.²² This framework emphasizes the importance of respecting sovereignty, territorial integrity, and promoting a strategic balance to deter actions that undermine global norms and legal frameworks.

In 2022, Japan flew two F-35s and moved fifty-five people to the Northern Territory in Australia for the country’s first international venture by their Joint Strike Fighters—marking post-war Japan’s first expeditionary air operation, except with the United States.²³ These forces then accompanied Australian F-35s back to Japan to participate in Exercise Bushido Guardian. The JDSC has further committed both countries to consulting with each other on contingencies that may affect their sovereignty and regional security interests and to consider joint response measures. The 2023 completion of the Japan-Australia Reciprocal Access Agreement (RAA) marked a further major milestone between the two countries—as well as it being Japan’s first defense treaty with an international partner since 1960—that underscores the strategic significance and the mutual commitment these partners have in deepening bilateral security cooperation.²⁴

For more than ten years, the Japan-Australia-U.S. trilateral relationship has demonstrated a consistent commitment to enhancing cooperation to promote the security, stability, and prosperity of the Indo-Pacific, and a growing desire to work together to address regional challenges. The Trilateral Strategic Dialogue (TSD), initiated in 2002, involves regular minister-level meetings to pursue an ongoing defense cooperative agenda that highlights the value of shared perspectives and a unified approach to enable more rapid responses to shared threats and interests. In late August 2024, a Chinese surveillance plane violated Japanese airspace, which was followed just five days later by the incursion of a Chinese survey ship into Japan’s territorial waters occurred shortly before the Australia-Japan 2+2 ministerial meeting.²⁵ Within a week of that meeting, Japan, Australia, and the United States initiated discussions aimed at enhancing command and control coordination between Australia’s Joint Operations Command and Japan’s JJOC, as well as exchanging liaison officers between these commands. Additionally, Japan and Australia agreed to jointly strengthen their deterrence capabilities in the region, leveraging their partnership with the United States as a shared ally. One significant initiative under consideration is Japan’s participation in U.S. Marine rotations in Darwin, which may include deployments of the Japanese Amphibious Rapid Deployment Brigade and F-35 fighter jet deployments, alongside an increase in joint exercises in and around Australia.²⁶

Japan is steadily expanding its network of defense cooperation arrangements in response to China’s increasing military assertiveness, while deepening partnerships where strategic interests intersect. Outside of deepening the U.S.-Japan defense partnership, Japan is also expanding ties with key partners in separate minilaterals with South Korea, Australia, the Philippines, and NATO, through the Asia-Pacific Four (or AP4) represented by Australia, Japan, South Korea, and New Zealand. A key focus of these partnerships is around capability development and interoperability, as well as joint training and exercises around shared interests, such as maritime security and cyber defense. Japan’s new RAAs with the United Kingdom and the Philippines, and negotiations with France are a case in point. These RAAs are emerging from shared concerns about the global implications of the deteriorating security situation in the South China Sea, driving the need for deeper cooperative activities and improved interoperability. Japan’s evolving approach to collective security, with a strong emphasis on deterrence, reflects both a response to growing regional threats and a proactive effort to shape the Indo-Pacific security architecture.

Australia’s Expanding Influence is Shaping Collective Deterrence

Australia is undergoing one of the most significant shifts in its defense strategic policy since the Cold War. Australia seeks a regional strategic equilibrium—enabled by a collective pursuit of deterrence—in which the sovereignty of all countries, large and small, is respected, and where all countries are free to pursue their national interests within the confines of a rules-based order.²⁷ The 2023 Defence Strategic Review recommended that the Australian Defence Force (ADF) “maximize deterrence, denial, and response options” by transforming into an integrated force capable of delivering effects across all domains.²⁸ The 2024 National Defence Strategy (NDS) took this recommendation a step further by adopting a strategy of denial, aiming to dissuade adversaries from taking actions harmful to Australia’s interests and regional stability.²⁹ To enable this strategy, the ADF is bolstering its capability to independently and collectively deter, in concert with the United States and partners like Japan.

Not only is Australia’s most recent national defense strategy complementary to the United States. NDS, but it has demonstrated a commitment to shared interests both in words and deeds. Australia is making substantial investments in both direct and indirect deterrence capabilities. Key among these investments is the acquisition of force projection capabilities from the AUKUS-enabled nuclear-power submarines, strike systems like the Joint Strike Missiles for the F-35, the acquisition of the Tomahawk cruise missile for Australia’s Hobart-class destroyers; and the land-based Precision Strike Missiles and Army Tactical Missile Systems for High Mobility Artillery Rocket Systems. This also includes ADF enhancements in passive defense through large purchases of smart sea mines. Investments are also being made toward enabling capabilities like MQ-4C Triton unmanned surveillance aircraft for enhanced situational awareness in the maritime domain. Former chief of the defence force general Angus J. Campbell reinforced the requirement to work collectively, because: “enhanced defence capability alone is insufficient. As a relatively modestly sized military, credible deterrence can only be delivered in partnership with those with whom we share common cause.”³⁰

Australia is playing an increasingly pivotal role in U.S. efforts to counter China’s military strategy and deter potential aggression. Critical to this arrangement is the bilateral Enhanced Force Posture Cooperation Initiative. Under this initiative, Australia hosts rotational U.S. Navy, Air Force, and Marine Corps elements for training and exercises for enhanced air, land, maritime, combined logistics, sustainment and maintenance, and space cooperation. These efforts are a significant expansion on force posture cooperation since they began in 2011. Australia and the United States are collaborating on infrastructure improvements to include base upgrades and expansion into new facilities, such as the use of Cocos Islands for extended maritime surveillance operations—stemming from the Pacific Deterrence Initiative.³¹ Funding upgrades to two bases in Northern Australia, for example, to support rotations of B-52 and B-1 aircraft and long-range bomber operations is another example of such posture investments.³²

An early milestone in the AUKUS partnership, Australia is set to host Submarine Rotational Force-West, with U.S. Navy Virginia-class attack submarines beginning rotational deployments by 2027.³³ In 2023, Australia completed its first-ever deep maintenance activity on a U.S. Navy MH-60R Seahawk helicopter, and in August 2024, U.S. and Royal Australian Navy personnel conducted joint maintenance on the USS Hawaii, a Virginia-class nuclear-powered submarine, and the first U.S. attack submarine to undergo such work on Australian soil.³⁴ These interoperability efforts are poised to greatly enhance American force projection capabilities across the Oceania region.

Australia has been a vocal advocate for the role of deterrence and the collective pursuit of a regional balance of power. Not only is Australia investing in significant minilateral arrangements like AUKUS and the Quadrilateral Security Dialogue, but it is active in deepening defense relationships beyond Japan, to include South Korea, India, New Zealand, Indonesia, the Philippines, Vietnam, Canada, and other partners in Southeast Asia. During consecutive Shangri-La Dialogues, Australian Deputy Prime Minister and Minister for Defence Richard Marles has argued that the need for new capabilities is “about Australia playing its part in helping contribute to the collective security of the Indo-Pacific . . . and to regional balance.”³⁵ Shortly after the 2024 Philippines-China Second Thomas Shoal incident, he argued that:

“all nations need to invest in a form of collective deterrence. We cannot just appeal to great powers to conduct strategic competition responsibly. That is too passive. Rather, we should seek, through our own national capabilities and regional architecture, to build a sustainable balance of power in the Indo-Pacific in which no one country in our region is militarily dominant. We must seek a set of conditions in the Indo-Pacific which constrain and ultimately preclude military options as a tool to seize or gain territory by ensuring that the risks of force outweigh any perceived benefit. We must all deepen our network of strategic partnerships in the Indo-Pacific that more effectively integrate our capabilities. This, of course, has a strong bilateral dimension.”³⁶

As Australia seeks to optimize and capitalize on available advantages and signal a commitment to upholding a favorable balance of power in the region, America remains indispensable to this approach. Australia and the United States are more firmly aligned than ever on the need to advance a collective approach to deterrence and security in the Indo-Pacific.

The Need for a Coalition Approach for Competition and Deterrence in the Indo-Pacific

The collective ambition of the United States, Australia, and Japan to counter China’s assertive behavior and safeguard a free and open Indo-Pacific region faces critical challenges. While trilateral and bilateral security cooperation between these nations has dramatically expanded, structural barriers hinder the creation of a more cohesive coalition capable of delivering effective deterrence. A core issue is the lack of a shared strategic framework to coordinate military capability. Although the countries share a vision for regional stability, they have not fully aligned their objectives, especially to prioritize specific threats and defining collective responses. Without clear and coordinated goals, policy alignment remains fragmented, diminishing the potential for a unified deterrent force.

Moreover, a critical weakness is the absence of a mechanism to integrate capabilities into a combined, operationally ready force. The lack of joint command structures, integrated planning, and synchronized military exercises in pursuit of key priorities, further undermines operational readiness. This leaves the coalition unable to have the level of readiness necessary to influence changes to the status quo. Despite pockets of excellence in elements among the United States, Australia, and Japan there is an insufficient level of interoperability across the human, procedural, and technical domains to enable the level of operational cohesion required for a credible deterrence posture.³⁷

Interoperability must be viewed as a strategic enabler, critical for leveraging collective military power in ways that promote mutual trust and operational effectiveness. Without an institutionalized means of integrating member states’ forces, efforts to coordinate joint missions, fill capability gaps, and execute joint deterrence measures remain disjointed. The absence of seamless interoperability undermines the coalition’s ability to demonstrate both the readiness and resolve necessary to sustain a credible deterrence posture. By prioritizing interoperability, and pursuing integration—the highest level of multinational interoperability according to the U.S. Army manual on multinational interoperability—a coalition can undertake more sophisticated and coordinated military operations, producing greater combat power, thus enhancing their collective capacity to deter.³⁸

A coalition approach allows for the pooling of military, economic, and political capital, amplifying the collective power of individual nations to coordinate and harness military capability toward common interests in a competitive security environment. A framework approach to collective deterrence enables the coalition to prioritize the most critical scenarios or threats—maritime security, territorial integrity, freedom of navigation or critical —lending greater credibility to its deterrence strategy. A unified stance among multiple nations also raises the costs for any potential adversary attempting to coerce or intimidate individual members, complicating adversarial strategies. This force-multiplying effect not only strengthens the credibility of the deterrence posture but also, forcing any act of aggression to be far riskier. Without the ability to act together coherently and effectively to achieve tactical, operational, and strategic objectives, the deterrence coalition risks: failure, legitimacy, preparedness, and potential undue harm to coalition forces.³⁹ 

The Way to Operationalize Coalition Deterrence 

The complexity of deterrence, especially in the context of Indo-Pacific dynamics, demands more than minilateral arrangements and fragmented alliances. To ensure a credible and effective deterrence posture, the growing deterrence coalition among the United States, Australia, and Japan should move toward a permanent joint force structure that enables operational cohesion and strategic alignment. The establishment of a multinational Joint Deterrence Force (JDF) could serve as the foundational mechanism for a robust, combined military framework capable of addressing shared regional challenges and deterring aggression collectively.

The Indo-Pacific security architecture, despite its extensive alliances and partnerships, lacks a dedicated mechanism to fully harness collective deterrence. The absence of a permanent, combined joint force undermines the ability to plan, coordinate, and execute joint operations effectively against shared threats. Misaligned defense capabilities, unclear political priorities, and a lack of integration across command structures and intelligence-sharing mechanisms hinder the coalition’s capacity to respond cohesively in times of crisis, increasing the risk of miscalculation and weakening the regional security dynamic. A JDF would provide the structural framework needed to operationalize coalition deterrence, institutionalizing collective security goals and enhancing military interoperability for combined force. By aligning strategic objectives and integrating capabilities, the JDF would enable proactive competition, faster resource mobilization, and improved crisis communication. This cohesive approach would strengthen the coalition’s deterrent posture and signal a unified commitment to regional stability, while also ensuring the capability to act decisively should deterrence fail.

In Pursuit of Coalition Deterrence

To operationalize a JDF, several key requirements must be met. First, there must be a shared strategic vision that aligns the goals and priorities of coalition members. Without a clear understanding of the threats to be deterred and the objectives to be achieved, the coalition will struggle to maintain cohesion and credibility. Second, the JDF must have institutionalized command and control structures. These structures would allow for real-time coordination, intelligence sharing, and joint decision-making. By centralizing command and control, the coalition could act with greater speed and effectiveness, ensuring that all members contribute to the deterrence effort in a meaningful way. Third, the coalition must prioritize interoperability across all military domains. This requires regular joint training and exercises, standardized equipment, and integrated logistics. Only by achieving a high degree of interoperability, can the coalition ensure that its forces can operate together seamlessly in response to any contingency. Lastly, the coalition must create a sustainable mechanism for burden-sharing. This involves ensuring that all members contribute fairly to the collective deterrence effort, both in terms of resources and political commitment. Burden-sharing not only strengthens the legitimacy of the coalition but also ensures that no single nation bears a disproportionate share of the costs and risks associated with deterrence.

The United States, given its military capabilities and global influence, is best positioned to lead the establishment of a Joint Deterrence Force with Australian support for the establishment of a coalition approach to regional collective deterrence. As the primary advocate for the rules-based international order and its extensive coalition-building experience, the United States has both the power, influence, and resources to drive this initiative forward. Australia’s leadership role within the region would further enhance the coalition’s legitimacy. As a middle power with deep connections to Southeast Asia and the Pacific Islands, Australia can act as a bridge between smaller nations wary of antagonizing China and the broader coalition effort. The United States, while essential, often faces resistance when its actions are perceived as overreach. Australia, on the other hand, brings a degree of regional trust and soft power that is crucial for cultivating a broad, inclusive coalition that resonates with the security concerns of its neighbors. Australia has also been a strong advocate for a collective approach to security and deterrence for free and open Indo-Pacific. Ultimately, no two countries in the Indo-Pacific share the level of depth and history of defense cooperation as the United States and Australia—both nations have fought together in every major conflict since World War I.⁴⁰

USINDOPACOM in Hawaii should serve as the logical headquarters for the JDF, given its role as a hub for multinational operations and its unifying alliance status. The decision to reconstitute U.S. Forces Japan as a joint force headquarters reporting to the Commander of USINDOPACOM, reinforces the primacy of this option from a command-and-control perspective. Today, Australia has a significant footprint at USINDOPACOM, with some forty-five members of the military embedded, including two two-star Generals.⁴¹ The establishment of a multinational JDF represents a pivotal opportunity to operationalize coalition deterrence in the Indo-Pacific. By creating a permanent, combined force structure, a coalition of like-minded nations will be far better positioned to deter threats, shape the regional security environment, and address specific security challenges too significant for any single or bilateral alliance to handle alone.

Defining the Features of Combined Joint Deterrence Force in the Indo-Pacific

Globally, a few examples of permanent combined joint forces provide meaningful insights about the institutional structure that would be required of forces operationalizing collective deterrence. No singular example in another region of the world can be used to mold the JDF, however two case studies exist that should inform the potential vision and scope of such a force in the Indo-Pacific, and provide meaningful lessons learned for the development of such a combined joint force.

Case Study 1: The Joint Expeditionary Force

The Joint Expeditionary Force (JEF) is a UK-led coalition of ten nations united by a shared commitment to respond swiftly to crises and to deter and defend against threats to the security of Northern Europe.⁴² Its geographic focus covers the High North, considered the European Arctic, stretching from the North Atlantic from Greenland in the West to the Norwegian-Russian border in the Barents Sea to the East, and South into the Baltic Sea region. JEF participant nations are all North Atlantic Treaty Organization (NATO) members, and they share a commitment to democracy, human rights, the rule of law, and regional peace in Northern Europe. As a collective international body, the JEF can respond quickly to emerging crises, which in turn reinforces individual national defense capabilities and contributes to bolstering NATO’s deterrence posture. Russia’s invasion of Ukraine has contributed to JEF Participant Nations’ commitment to unified cooperation and collective strength as enablers of regional security.⁴³

When the JEF was launched in 2014 at a NATO Summit in Wales, the UK government described it as “a pool of high readiness, adaptable forces that is designed to enhance the UK’s ability to respond rapidly, anywhere in the world, with like-minded allies, or on behalf of international organisations such as the UN or NATO.”⁴⁴ The JEF emerged from NATO’s Framework Nations Concept designed to foster multinational defense collaboration by organizing functional groupings around a larger ally.⁴⁵ NATO’s vision was that the larger allies who maintain a broader spectrum of capabilities could provide a framework for other like-minded allies to plug into.⁴⁶ The primary catalyst for the JEF’s creation was the evolving security environment in Europe, particularly Russian aggression in Crimea and broader Eastern Europe, highlighting the need for rapid, flexible military responses from Europe. The UK’s involvement in operations in Afghanistan and Iraq had led to the disbandment of their Joint Rapid Reaction Force, which had been established in the mid-1990s to provide capabilities for military and humanitarian crisis.⁴⁷ Renewed geopolitical regional threats made it clear that a high-readiness multinational force was necessary for deterrence and crisis response.

As the framework nation, the UK is both the operational and institutional lead. The JEF Standing Joint Force Headquarters and the JEF Secretariat, located at the UK’s Permanent Joint Headquarters in Northwood, London is where all overseas military operations are planned and controlled.⁴⁸ The JEF is commanded by a British two-star Major General and supported by upwards of 150 multinational personnel.⁴⁹ As highlighted by the UK Parliament, the JEF is not a separate standing army or fighting force, but rather a collection of units that train and exercise together that serves as a forum for discussion of defense and security issues between allies.⁵⁰ As such, the UK is not given forces, nor are any forces identified. The JEF utilizes each nation’s existing high readiness forces and upon consultation and sovereign national decision of the participants, deploys them, as and when required, operating under an “opt-in” structure.⁵¹

The JEF is complementary to NATO aims and objectives, but it is not part of NATO. The coalition operates independently in its own right but can also do so seamlessly with NATO. Members are not treaty-bound, and the JEF mechanism is designed to supplement NATO and participant nations’ own response capabilities. The JEF was specifically designed to enable swift responses to security threats and crises below the threshold of conventional war. Operating independently from NATO’s formal structures, it allows decision-makers to act more flexibly and without the need for consensus, ensuring faster, more adaptable engagement in rapidly evolving situations. The JEF fills a niche absent in NATO, the ability to take collective action, without the delays of consensus negotiations and potentially triggering “Article 5” —their principle of collective defense.⁵² This approach allows members flexibility to contribute forces, resources, and expertise as needed, depending on the mission or activity. If there is an agreement among two or more JEF members to work together, a JEF operation will proceed, and force contributions, support, and lead elements execute.⁵³

Since the 2018 signing of the Comprehensive Memorandum of Understanding, the JEF has progressively expanded its primary operational focus to include defending critical national infrastructure and strengthening force integration through joint military exercises.⁵⁴ This evolving mandate reflects the JEF’s adaptability to emerging threats in the region, ensuring preparedness in both conventional defense and hybrid security challenges. This has been demonstrated through the JEF’s early support for Ukraine, providing military, political, humanitarian, economic, and legal assistance, signing the international Joint Declaration of Support for Ukraine, and efforts to strengthen security cooperation. Ukraine is to observe JEF exercises in 2024 and 2025, with the intention to “increase interoperability, and enhance the capability of the Armed Forces of Ukraine.”⁵⁵

JEF operations are based upon the JEF Operating Framework to meet the needs of its participant nations in both peacetime and crisis situations. Thus, persistent JEF Integration Options (JIOs) and proactive JEF Response Options (JROs) are developed as planned integrated military activities to support a range of strategic pursuits to enhance multilateral capabilities, to reassure nations and deter aggression, and to deploy below the threshold of war throughout the continuum of competition to conflict. JROs are designed for optimal alignment to the JEF participant nations’ national defense plans and the NATO family of plans.⁵⁶ During peacetime, members integrate their capabilities to demonstrate unity and cohesion through joint training and exercises, and to continually innovate ways to enhance their operations for cohesiveness and effectiveness. In November 2023, JEF Defense Ministers agreed, for the first time, to activate a JRO, toward the protection of critical undersea infrastructure, and again in 2024, as a series of activities to include exercises, and the integration of new technologies.⁵⁷

The JEF is more than a joint expeditionary force, it’s a dynamic mechanism for member nations to contribute to regional security and deterrence, enhance their own capacities, and serve as a forum to collaborate and coordinate security threats.

Case Study 2: The Combined Maritime Forces

The Combined Maritime Forces (CMF) is the world’s largest multinational naval partnership and maritime coalition. Its 46 members operate a network of influence within an area of responsibility (AOR) covering approximately 3.2 million square miles of international waters from the Red Sea to the Indian Ocean.⁵⁸ The AOR encompasses three of the top six crucial maritime choke points in the world, including the Strait of Hormuz, the Suez Canal, and the Strait of Bab el-Mandeb.

The U.S.-led CMF was established in 2001 by twelve like-minded nations as a Maritime Security Operations (MSO) combined task force outside the Arabian Gulf to counter the threat of international terrorism at sea post-9/11.⁵⁹ This was an expansion of a U.S. Navy formation under Operation Enduring Freedom. However, the CMF’s origins date back to 1991, under Operation Desert Storm, when the United States called for the first “coalition of the willing.”⁶⁰ Many of the original CMF nations were participants in the Desert Storm coalition, contributing to the CMF’s extensive multinational operational history.

The CMF’s goal is to ensure regional freedom of navigation by combating piracy, smuggling, terrorism, and other threats, while also supporting the strategic interests of partner nations.⁶¹ This includes the capacity-building of its members. CMF operationalizes this mandate through five Combined Task Forces (CTFs) that focus on both regional and functional threats and challenges. The CTF focus areas include: CTF-150 MSO outside the Arabian Gulf, CTF-151 counter-piracy, CTF-152 MSO inside the Arabian Gulf, CTF-153 Red Sea Maritime Security, and CTF-154 Maritime Security Training.⁶² CTFs are commanded on a rotational basis among members, based on interest, experience, and resources, which require the members to devote additional personnel to the task force staff. Each CTF has a unique history, member composition, missions, training, exercises, and interdictions or interceptions focus.

The CMF maintains an active and strategic public affairs presence across social media platforms, effectively showcasing key activities, leadership transitions, and operational successes. This outreach bolsters transparency, fosters a global awareness of CMF initiatives, and underscores the tangible contributions of member nations. By highlighting these achievements, CMF not only strengthens its international reputation but also enhances deterrence by demonstrating collective maritime security capabilities, as well as highlighting individual national achievements at a global stage that improves their military operational credibility.

The CMF is commanded by a three-star U.S. Navy vice admiral, who also serves as commander of U.S. Navy Central Command and U.S. 5th Fleet, co-located at U.S. Naval Support Activity Bahrain. CMF’s deputy commander is a UK Royal Navy commodore, and other senior staff roles at the headquarters are filled by personnel from member nations, with a large share provided by Australia, France, Italy, and Denmark.⁶³ At their most recent annual Maritime Security Conference, CMF Commander and Vice Admiral George M. Wikoff articulated the combined force’s unique command structure, “I see myself as the CEO and you are the board of directors. And as that board of directors, you tell me what we want to achieve, and it is up to me and the CMF organization to deliver.”⁶⁴ The CMF conference functions as a high-level consultative forum, providing an opportunity to assess past initiatives, plan strategic objectives for the coming year, and explore new avenues for strengthening maritime security and partnerships.

Nations join the CMF with a shared commitment to upholding the international rules-based order, safeguarding the free flow of legitimate commerce, ensuring regional maritime security by deterring illicit activities, and maintaining readiness against emerging threats. Recognizing that no single nation can unilaterally ensure maritime security, member states contribute forces and personnel to collectively address significant threats. Membership in the CMF also supports military objectives such as capacity-building, gaining operational experience under different command structures, and enhancing interoperability with nations outside formal alliances. In November 2023, India transitioned from associate partner to full CMF membership, becoming the tenth Indo-Pacific participant alongside Australia, India, Malaysia, New Zealand, the Philippines, South Korea, Singapore, Sri Lanka, and the United States. India’s decision was framed as a strategic move to deepen interoperability with the United States and advance the sophistication of their defense partnership. India’s participation is also key to advancing their security objectives, with maritime partnerships playing a crucial role. By April 2024, the Indian Navy completed its first mission under a foreign flag, interdicting the narcotics trade under CTF-150, led by the Canadian Navy.⁶⁵

Institutionally, CMF membership is voluntary, tiered, and flexible; having no elaborate political or military mandate, no set working language, or established contribution requirements to join or participate.⁶⁶ Instead, each nation’s contribution varies depending on its ability to contribute assets and the availability of those assets at any given time. As such, contributions vary from the provision of one or many liaison officers at CMF headquarters to the supply of warships or maritime reconnaissance aircraft in task forces. For instance, the CMF can call on warships not explicitly assigned to CMF to give support, which may be offered if that nation has the time and capacity while undertaking national tasking.⁶⁷ The contribution philosophy is that members “will never be asked to do more than what their national mandate allows.”⁶⁸

The CMF has proven highly effective in the Middle East—serving as a critical mechanism for collective action. In the last ten years, membership has risen more than 50 percent, representing key regional players like India; and in the last two years, two new task forces were stood up, expanding the scope of maritime security operations in the region. The CMF contributes to security in direct ways—in 2021, the CTF 150, under Royal Canadian Navy command, led to a record-setting seizure of 2,835 pounds (1,286 kilograms) of heroin during a counter-smuggling operation in the Arabian Sea.⁶⁹ Examples like this are making a salient impact on impeding drug trafficking, which is often used to finance terrorism in the region. This essential work is indirectly contributing to enhancing regional deterrence of threats against freedom of navigation and legitimate free flow of trade.

Lessons from the JEF and CMF and Critical Features of an Effective Coalition

The JEF in Europe and CMF in the Middle East serve similar functions as multinational military frameworks dedicated to complex systemic regional threats focused on delivering discrete capabilities for specific mission sets. However, they achieve their aims through unique institutional approaches. Numerous lessons and defining features of these cooperative bodies can inform the scope and structure of an effective Joint Deterrence Force in the Indo-Pacific region.

Establish a Clear Vision and Policy Direction for Unity of Effort 

A clear vision ensures all members are aligned and working toward the same objectives and preventing misunderstandings of regional neighbors. A shared vision also enhances coordination among diverse members, fostering cohesion and effective collaboration in the development and participation of activities from training to deployment. Achieving campaign objectives requires civilian-military coordination to ensure continued support and strategic alignment. However, this kind of unified effort is traditionally challenging to accomplish. The JEF’s political-military connection is rooted in its public policy direction and accompanying classified military strategic objectives. JEF holds regular senior political, policy and military meetings to develop and refine JEF’s coordinated responses to meet evolving challenges and strategic priorities.⁷⁰

The CMF and JEF demonstrate an overriding unity of strategic purpose, which is essential for coalition unity of effort. Kathleen McInnis argues these critical components are essential to coalition success because, as mission difficulty and risk increase, coalition cohesion decreases without an overwhelming threat.⁷¹ Without shared interests, nations are unlikely to prioritize collective goals over their own, leading to fractures among partners. Building agreement into military coalitions requires compromise, which can in turn, constrain operational-level effectiveness. Having shared interests, such as a perceived or real threat, is crucial for achieving strategic-level consensus on the purpose, goals, and end state of coalition operations, which is essential for coalition formation and success.⁷² Ultimately, the stronger the unity of interest, the greater the commitment of members to a coalition.

Develop a Political Identity and Foster Cohesion  

Both the CMF and JEF emerged from preexisting organizations with established operational histories in their respective regions or thematic areas, drawing on their original memberships. For instance, the political cohesion of the JEF is a function of its “like-mindedness” as NATO allies and close geographic proximity to each other. Similarly, the backbone of CMF membership was united against the common threat of terrorism, and their identity was formed out of common values and interests. This feature of the CMF’s identity, coupled with its flexible and member-driven agenda, has enabled it to evolve with changes to the security environment, re-prioritize its mission based on current threats, and maintain unity and cohesion.

A strong, shared identity is key to building cohesion within a Joint Deterrence Force (JDF). Greater transparency, as seen with the CMF and JEF, can help strengthen this identity. Both organizations maintain public visibility through joint statements, press releases, active websites, and social media. This openness raises awareness of member contributions, enhances credibility, and legitimizes the coalition's mission, fostering a sense of unity and purpose among participating nations.

Leadership, Membership, and the Pursuit of Interoperability

The CMF and JEF are led by nations with significant global influence, robust military capabilities, and extensive experience in multinational coalitions. The United States and the UK, as leaders, provide the strategic vision, political will, and commitment to collective security essential for effective coalition leadership. Their ability to manage members' differing risk tolerances and operational caveats (i.e. scoping directives on force employment) is crucial to maintaining cohesion and operational success.

While the CMF and JEF take different approaches to membership, both balance the need for (such as high cohesion) over quantity (that is, highly inclusive). The CMF, for instance, operates without a fixed language, formal membership criteria, or mandatory contributions—nations participate voluntarily by committing forces or personnel. This flexibility can challenge cohesion and interoperability but also allows for broader participation. Effective coalitions must carefully balance political and military participation, as greater membership does not always equate to more effective missions. The strengths of the CMF and JEF lie in their flexible, opt-in formats, which allow nations to contribute based on specialization, interest, and capability. This structure not only generates force-multiplying effects by matching capabilities but also enables smaller nations to participate in ways they otherwise couldn’t, enhancing capacity, interoperability, and the overall legitimacy of the coalition.

Overall, the strengths of both the CMF and JEF in their opt-in membership format contribute to the coalition based on a participating nation’s specialization, interest, and capability, which enables a number of benefits. First, flexible participation in a structured format allows the CMF and JEF to match the capabilities and contributions of larger and smaller nations within their unique task force groupings to generate force-multiplying effects. It further supports smaller participating nations to contribute capabilities or capacities to tasks they would otherwise not be able to generate, and thus, the structure provides a mechanism for nations to work together, build capacity, interoperability, and greater legitimacy of the coalition.

Implementing a Joint Deterrence Force

A future Joint Deterrence Force should encompass a comprehensive and integrated approach to collective security, enabling its members to collectively shape the environment and deter aggression through credible and coordinated military activities and operations. The JDF would be designed to complement other international frameworks and avoid duplication, and should support other bodies, such as the United Nations or NATO, as appropriate or required. The JDF should focus on developing joint operational readiness, ensuring high levels of interoperability across air, land, sea, cyber, space domains, and unifying strategic goals among participating nations. Members would contribute the capabilities that would enable the JDF to plan, exercise and operate effectively together. The JDF should aim to complement member nations’ direct and indirect deterrence capabilities. This approach would be enabled through enhanced shared situational awareness with greater interconnectivity and integration enabling common solutions to common challenges. The JDF would serve as a vital forum for political consultations on defense and security challenges affecting the region. This political cohesion would not only enhance the deterrence posture but also fortify the legitimacy and credibility of the coalition’s vision of a free and open Indo-Pacific.

Several key features directing the mechanics of the JDF require more extensive consideration to address unique facets of regional geopolitics and deterrence requirements. Those include formality and decision making, contribution of members, and identification of potential task groups around functional security threats or in sub-regions. A JDF should consider an opt-in, flexible arrangement, offering levels of membership, that is grounded in a memorandum of intent establishing clear member contributions, as well as roles and responsibilities. To this end, JDF participants should not be obliged to contribute forces to any given activity or deployment; instead, it remains a sovereign national decision for participants to contribute, within their respective legal frameworks. As such, the JDF operations and force deployments would only require consensus among two members to pursue an activity or operation, similar to the JEF. Lastly, to enhance cohesion, defense secretaries and ministers should meet annually, and the JDF should hold regular political, policy, and military working group meetings at a senior level to maintain a shared understanding and maximize coordinated and synchronized responses to evolving challenges.

Conclusion

Deterrence is complex and coalitions are hard. Winston Churchill is quoted as saying, “There is at least only one thing worse than fighting with allies, and that is fighting without them.”⁷³ History tells us that managing and operating in a military coalition is very challenging due to the extraordinary requirements around multinational cooperation, coordination, and cohesion politically and militarily at the strategic, operational, and institutional levels. An ambitious international response toward the goal of an open and free Indo-Pacific regional order is necessary. The United States and its allies possess both the capabilities and an emerging framework for action; what remains essential is the leadership, trust, and unified political will to assert their collective influence in shaping the future of the international order.

Notes