Northeast Asia Is for Deterrence and Southeast Asia Is (Mostly) for Freeriding: Appreciating Divergent East Asian Approaches to Order, Uncertainty, and Contestation

This publication is a product of Carnegie China. For more work by Carnegie China, click here.

In recent years, actors in Northeast Asia have made a series of efforts to invest in defense capabilities, enhance security cooperation, and develop means to resist economic coercion. Almost none of the Southeast Asian states has initiated similar major security-related initiatives other than broadly modernizing existing military capabilities. Northeast Asian governments and publics seem invested in deterrence with respect to China by securing continued, active U.S. participation in regional affairs, among other objectives. Most Southeast Asian states prefer to maintain the existing order, including its association with a U.S. presence, but appear less inclined toward deterrence. Publicly, they neither oppose nor support the behavior of their Northeast Asian neighbors but also are passive about reducing regional tension and friction. Most Southeast Asian states behave as if the actions of their Northeast Asian neighbors and the Philippines will be sufficient to maintain a regional status quo from which they can benefit.

This divergent behavior between Northeast and Southeast Asia looks somewhat surprising at first glance. Actors in both subregions of East Asia benefit from clear, established practices, rules, and institutions that promote integration, predictability, and restraint on state behavior, especially when it comes to major powers. Such conditions helped undergird the prosperity and relative stability the region has enjoyed since the drawing-down of the Cold War—domestic inequality and environmental degradation notwithstanding. Southeast and Northeast Asian actors share a stake in maintaining this status quo, particularly in light of mounting common challenges. These challenges include intensifying U.S.-China competition, increasingly tense territorial disputes, more frequent economic coercion, declining interest in economic liberalization, supply chain disruptions, and less certainty over major power policy directions. Yet responses to these developments in East Asia depart along broadly subregional lines.

Status Quo Maintenance in Northeast Asia

Japan, South Korea, and Taiwan have been openly enhancing existing alliances and developing new security partnerships over the past several years, especially in the face of growing pressure from China and concerns about U.S. commitment. Seoul and Tokyo have broadened the scope and scale of their cooperation in their bilateral alliances with Washington, and have expanded security coordination with each other despite persistent differences surrounding Japan’s colonial legacy in Korea. Japan has established new security partnerships with Australia, the Philippines, the United Kingdom, Italy, and India, while supporting maritime surveillance and coast guard capacity-building in Indonesia, the Philippines, Malaysia, and Vietnam. South Korea has sought to assist in improving coast guard capability as well as upgrading of military capabilities across Southeast Asia through arms sales. Seoul and Tokyo also have upgraded some degree of coordination with NATO. Taiwan has focused on tightening security, military, and technological cooperation with the United States, and has expanded informal security dialogues with Japan, South Korea, and the Philippines despite an absence of formal, official diplomatic ties.

Moreover, these same Northeast Asian governments have taken steps to significantly expand their military capacities. Defense budgets in Japan, South Korea, and Taiwan have increased by 30 percent, 25.1 percent, and 50 percent, respectively, since 2016, alongside investment in research and development on defense-related technologies. All three have devoted resources to expanding their cyber defense and coast guards. Taiwan further moved to reintroduce conscription to increase troop numbers, expand civil defense to improve resilience to attacks, and build up its defense industry, especially in critical technologies from aircraft to missiles to shipbuilding. Such actions have introduced more advanced combat capabilities as well as expanded coast guard capacities for safeguarding maritime territory. Japan, South Korea, and Taiwan are further investing in supply chain resilience, economic diversification, and devising options for actively mitigating as well as withstanding economic coercion.

Actions by Seoul, Taipei, and Tokyo seem to center on a belief in the need to more effectively deter Beijing from potentially challenging the prevailing status quo. To do so, they have sought to increase risks to the use of force and deny opportunities for coercion. By building up alliances and security partnerships along with enhancing military capabilities, they aim to greatly increase the potential costs of using force to resolve disputes, hoping to discourage an increasingly militarily capable China, as well as North Korea, from taking such actions. Escalating violence from the East China Sea through Taiwan and the South China Sea will threaten the sea, air (see Figures 1), and telecommunications (see Figures 2) links on which Japan, South Korea, and Taiwan depend. Beijing is reportedly already able to impose pressure on the laying, maintaining, and repairing of submarine cables connecting Northeast Asia via the South China Sea. An attack by China could inflict devastating damage on Taiwan; similarly, a North Korean assault could greatly harm South Korea or Japan. Attempts to bolster economic and supply chain resilience to deny Beijing’s easy use of economic pressure to compel compliance also better place Northeast Asian actors to resist coercion.

Having Their Cake and Eating It in Southeast Asia

Most Southeast Asian states are much more restrained than their Northeast Asian neighbors are on security initiatives and building up defensive capabilities. Arms procurement and defense expenditures have grown in Southeast Asia at an average of 11.6 percent between 2023 and 2016, but these outlays appear to be more about force modernization and local territorial defense, with a focus on each other or internal security. Cooperative security initiatives such as those based around the ASEAN (Association of Southeast Asian Nations) Defense Ministerial Meetings are incremental and modest in ambition, with less appetite for building mechanisms or updating ASEAN organizationally. Negotiations for some sort of Code of Conduct over the South China Sea appear stalled, even if officials prefer to tout progress in public without reference to substance or specifics. Military exercises, even large-scale ones, regularly occur, but are issue-specific like antipiracy, humanitarian assistance and disaster relief, or counterterrorism, rather than being geared systematically toward bolstering regional security architecture.

The Philippines is the exception in Southeast Asia. Over the past few years, it has upgraded the scale and scope of its defense cooperation with not only the United States but also Japan, South Korea, and Australia to signal the potential costs of using force against the Philippines’ interests. The Philippines upgraded alliance cooperation with the United States with an eye to contingencies involving the South China Sea and Taiwan, notably through the Enhanced Defense Cooperation Agreement. Activities it has undertaken include hosting increasingly sophisticated U.S. forces and prepositioning U.S. military equipment. Manila further has sought new security cooperation opportunities with non-U.S. partners. It signed visiting forces and training agreements with Canberra and Tokyo while acquiring military, coast guard, and maritime surveillance equipment as well as training from Tokyo and Seoul. The Philippines also has purchased BrahMos antisurface supersonic cruise missiles from India.

Nevertheless, and in contrast with the Philippines, most Southeast Asian countries stand to gain from their relative inaction even as they benefit from the current regional architecture. Successful Northeast Asian and Philippine efforts, perhaps in conjunction with the United States, to deter China from changing or challenging the status quo have allowed Southeast Asia to continue enjoying the prevailing regional order. These countries do not have to foot the costs of this deterrence, commit to reforming ASEAN, or invest in institution-building. At the same time, they are able to avoid the risk of backlash from Beijing by claiming noninvolvement in anything China finds objectionable. Other Southeast Asian capitals can even point to Manila and suggest to Beijing that if concessions are not forthcoming, they may follow the Philippines in adopting positions that China may find less preferable. Silence enables Southeast Asian states to maximize benefits by pushing the costs and risks of order maintenance onto Northeast Asian states, the Philippines, and the United States, especially when they believe their actions are of limited broader consequence. That said, it is by no means certain that this inaction will be free from repercussions.

Given where their interests lie, it is unsurprising that most Southeast Asian states prefer to hide and make opportunistic arrangements for immediate gain. Even considering the impact of Beijing’s Belt and Road Initiative, Europe, the United States, and Japan remain by far the largest investors across Southeast Asia, followed by China and South Korea, albeit with some cross-country variation. China is the largest bilateral trading partner in goods for each Southeast Asian state, with the United States not far behind, although ASEAN countries collectively remain each other’s largest trading partner in goods. Trade in services vary across the region, with less clearly dominant partners. Southeast Asian states further stand to pick up investment from corporations derisking and diversifying from China, including those from Japan, South Korea, and Taiwan. Southeast Asian states prefer that the current trends in stability, order, and prosperity accompanying active U.S. and allied engagement persist, but wish to avoid offending China and even Russia.

In addition, Southeast Asian states are suspicious of being entrapped by Washington’s potential adventurism, while also being skeptical of U.S. commitment, and by extension the actions of its allies and partners. There are lingering apprehensions toward the United States for its excessive intervention in Southeast Asia during the Cold War whether in terms of supporting repression or exacerbating conflict and, in states with large Muslim populations, a sense of U.S. Islamophobia. What appears to be unequivocal support for Israel’s disproportionate treatment of Palestinians drives further wariness about being too closely and openly aligned with the United States. This mindset persists despite the pressure that maritime Southeast Asian states face in the South China Sea and mainland Southeast Asian states encounter along major rivers. Such sentiments are longstanding, but the actions of U.S. administrations since the early 2000s and complicity in Israeli actions in Gaza since 2023 have reinforced these beliefs among both elites and the public. Even Singapore’s substantive security, economic, and other forms of cooperation with the United States reflect a desire to entice Washington to continue its regional commitments but avoid Singapore’s own entanglement in U.S. policies.

Implications of Divergence

Despite the intertwined interests of Southeast and Northeast Asian states in the prevailing international order, the considerations of states in each subregion complicate coordination, much less cooperation. Alignment, if not alliance, with the United States and direct pressure from China make deterring Beijing’s efforts to adjust the status quo a more straightforward proposition for Northeast Asian actors and the Philippines. Northeast Asia’s greater capability and wealth also make it easier to undertake and fund such a policy direction. The rest of Southeast Asia can simply allow and sometimes even quietly encourage their neighbors to bear the risks and costs of deterrence while profiting from the status quo. However, this passivity means they may have little say in the direction and evolution of the current order, and must perhaps hope for the benevolence and largesse of whichever actor or group of actors that end up shaping what comes next.

Contrasting actions in Southeast and Northeast Asia each bring their own sets of potential pitfalls. Passivity in Southeast Asia can end up inviting rival major powers to see the region as one where they must compete harder to avoid losing out, possibly increasing pressure on Southeast Asian states and reducing their space for maneuver. Maintaining silence and seeking advantage from working with all sides—behaviors some characterize as hedging—presumes that such variability is acceptable to contesting major powers and that timely mitigating action always can be taken to avoid trouble. Even if Washington and Beijing are currently open to giving Southeast Asian states some leeway to maneuver, intensifying major power competition can challenge this position and can make self-serving actions look like unreliability or even duplicitousness. Withholding more active positions can avoid friction in the short term, but this requires an optimism that the effects of major power contention will not leave Southeast Asian states worse off and preparation for more tumultuous future circumstances are unnecessary.

Northeast Asia and the Philippines’ more active stance may work to help to discourage unilateral efforts to change prevailing conditions; nonetheless, it is susceptible to all the usual downside possibilities associated with deterrence. These countries must calibrate the combination of credible threats and assurances accurately and appropriately, even as conditions constantly change. Getting one or both wrong can end up in deterrence failure and prompting escalation instead, at which point these actors and their main partner, the United States, must decide whether to follow through on threats or back down and accept accommodation. Then there is the issue of signaling to make sure that the side being deterred, China, is clear about cautious, pro–status quo intentions and does not interpret defensive moves as aggressive, which it already may be doing. It is difficult to make sure that all these elements are in place when China is rapidly increasing its coercive capabilities but faces growing domestic economic and demographic obstacles while limiting communication and transparency.

Transparency and Limited Options

For more Southeast Asian states to have more active roles in managing order in East Asia, their leaders and populations must understand the stakes they have in regional and global stability as well as the cumulative effects of their actions (or inaction). Perceptions of current or future dependence on other major actors, especially China, as well as impotence tends to further discourage initiative. Southeast Asian states that prefer inaction, even as they seek economic gains and hope to maintain the status quo, behave as if major powers will consistently engage in self-restraint and mutual accommodation, allowing them to keep accruing benefits at little risk and cost. Such conditions, which privilege absolute gains, offer few incentives to insure against a more turbulent world and region. Whether the situation can persist as major power competition intensifies and players become more concerned with relative gains, or if a major power that is less invested in an open international order prevails, remains an open empirical question.

Changes to such relatively passive perspectives can persuade Southeast Asian states to work on overcoming their collective action and coordination problems over various concerns and perhaps give more substance to claims of “ASEAN centrality.” In addition to changes in external outlooks, Southeast Asian states will need to address a lack of political will, given either domestic political and social instability or tentativeness associated with leadership transitions. Should Southeast Asian states work together more effectively, perhaps even to collectively bargain, they could leave a greater imprint on regional and global developments. For Southeast Asian states to become more active in managing their own region and be willing to bear some of the associated burdens, likely will need to face some significant shock that does not first irreparably damage regional order. Otherwise, they will be tempted to focus on immediate economic gains and domestic issues while avoiding having to deal with deeper, longer-term complications of ASEAN dysfunction and the dangers of major power rivalry.

Nonetheless, actors in Southeast and Northeast Asia appear committed to their current trajectories, especially given the absence of clear incentives to change tack. Southeast and Northeast Asian states essentially are taking different bets on the future in the face of heightened uncertainty. It appears that the divergence described above will persist, at least for the foreseeable future. To better manage the attendant risks in the absence of an appetite for initiative in Southeast Asia, regional actors may wish to be more transparent about their goals and intentions to reduce room for miscalculation. Such moves cannot fundamentally reduce rising tension in the maritime arc stretching from Japan to Indonesia, but greater transparency is an attainable first step toward some management of differences. Other than that, China as well as United States and its allies and partners in Northeast Asian and beyond may need to repeatedly test each other before coming to some sort of mutual understanding in East Asia and elsewhere.