Tracking Japan’s Military Strike DebateBy James L. Schoff, Hana Anderson, and David Song

Occasional resurfacing of the so-called enemy base strike debate often produces alarmist headlines and predictions of a remilitarized Japan, but in fact this debate has been percolating for decades and is still rooted in Japan’s defensive military politics.1 Enemy base strike capability (teki kichi kōgeki nōryoku) currently refers to Japan’s Self-Defense Forces (SDF) possibly acquiring the means to attack missile launch sites in enemy territory for self-defense. It is also sometimes referred to as missile prevention capability (misairu soshi nōryoku).

Japan’s debate over the constitutionality of potentially offensive military strikes dates back to a 1956 statement made on behalf of then prime minister Hatoyama Ichirō. It said that striking enemy missile bases should be permissible within certain limits: Japan can take only the “minimum measures unavoidably necessary” when “no other measures” of self-defense are available in the face of an “imminent illegal invasion.” This statement became the bedrock of all future deliberations that sought to clarify Hatoyama’s interpretation, as part of a broader process to reconcile Japan’s exclusively defense-oriented security policy (senshū bōei)—which prohibits the procurement of certain offensive weapon systems—with pressures caused by the continuing evolution of modern warfare.

The strike debate began as a hypothetical exercise but became increasingly concrete from the late 1990s with a growing North Korea threat. China’s recent military rise and North Korea’s continued missile and nuclear development have put renewed focus on this issue, and it will feature prominently in the U.S.-Japan Roles, Missions, and Capabilities (RMC) dialogue that is taking place now through 2022.

Three main components make up the strike debate: When exactly can Japan use force overseas for self-defense? How should “no other measures” be defined? How are strike capabilities for self-defense reconcilable with the general belief that Japan’s constitution prohibits offensive war-waging weapons? More recently, specific terminology has been used to help differentiate between the subtle nuances of what should (and should not) be allowed, such as how a “preemptive strike” might differ from a “first strike,” or a “standoff weapon” might differ from one meant to strike an enemy base.

The following historical timeline of statements by senior Japanese officials helps answer these questions by highlighting relevant quotes from politicians (with original Japanese and our English translations) and providing necessary background on the context behind their statements. A glossary is included at the end, providing our assessment of what certain Japanese terms mean with regard to the government’s evolving defense policy and military procurement plans.

1 This digital feature builds on earlier work in James L. Schoff and David Song, “Five Things to Know About Japan’s Possible Acquisition of Strike Capability,” Carnegie Endowment for International Peace, August 14, 2017,


Foreign Minister Funada Naka, on behalf of Prime Minister Hatoyama Ichirō

Cabinet Committee in the House of Representatives
February 29

The 1956 Hatoyama statement sets the foundation for future debate on enemy base strike capabilities, outlining the key constraints to any strike acquisition. As the first official government statement, it highlights three conditions for a constitutional strike: 1) there must be an “imminent illegal” attack on Japan, 2) all Japanese capabilities must be below the threshold of “minimum measures unavoidably necessary” for protection, and 3) strikes are only permitted if “no other measures are available” to defend Japan.

“In the event that an imminent illegal invasion is carried out against our country, and if this invasion is an attack on our country’s soil through guided missiles, I cannot believe that it is the constitution’s intention for us to sit and wait for our own destruction. In such an event, I think that taking the minimum measures unavoidably necessary to protect against such attacks—such as attacking missile bases in order to defend against missile attacks only if no other measures are available—is legally within the scope of self-defense and could be considered a possibility.”
Citation: Hearing before the Cabinet Committee in the House of Representatives, 24th Diet (1956) (statement by Hatoyama Ichirō, delivered by Foreign Minister Funada Naka, February 29, 1956),

Japan Defense Agency (JDA) Director General Inō Shigejirō

Cabinet Committee in the House of Representatives
March 19

Inō parses the Hatoyama statement from the Japanese constitution’s restrictions against possessing weapons that can “offensively threaten” neighboring countries. Rather than directly address how base strike capabilities can avoid being offensively threatening, Ino instead argues that it is an improbable hypothetical scenario for Japan to have no assistance from the UN, the U.S.-Japan alliance, or other forms of external help when under attack—thus relying on the “no other available measures” clause to avoid contradiction between contemporary constitutional interpretation and the Hatoyama statement.

“However, such circumstances [described by the Hatoyama statement] are unlikely to occur as real problems today, and it is not the constitution’s intention for our country to possess weapons during ordinary times that can attack and offensively threaten other countries just because of this [previously described] hypothetical danger. In this way, we think that these two concepts [of Hatoyama’s statement and not possessing weapons in peacetime] are two separate problems and do not contradict each other.”
Citation: Hearing before the Cabinet Committee in the House of Representatives, 31st Diet (1959) (statement by JDA Director General Ino Shigejiro, March 19, 1959),

Japan Air Self-Defense Force (JASDF), Air Staff Office

In the midst of ballistic missile defense (BMD) discussions in 2005, the Sankei Shimbun published an article revealing that the JDA conducted an enemy base strike study in 1994 that was never disclosed to the public. The study simulated using F-4 fighters to carry out strikes against missile bases, but concluded that Japan alone does not possess the capabilities to reliably conduct successful strikes and that Japan must depend on the United States for such missions.

The revelation by Sankei Shimbun caused a minor uproar among the Japanese public, leading then JDA director general Ōno Yoshinori to hold a press conference clarifying both the constitutionality of base strikes and the current lack of Japanese capability to conduct such strikes. It also supported the general opinion of U.S.-Japan role-sharing, in which the United States is the offensive “spear,” backed by Japan’s “shield” role.

“While we possess the capability to bomb [enemy] bases, it cannot be said that we can reliably conduct systematically effective strikes with JASDF’s [current] information collection and electronic combat capabilities. . . .

Without answering whether [we] have the capability to preemptively strike enemy bases, we expect the American military to strike foreign territories.”

Citations: “1994 JDA simulation explored preemptive strike against North Korean missile threat,” Sankei Shimbun, hosted on Internet Archive, published April 8, 2005,;

Ōno Yoshinori, “Director Ōno press conference summary,” Japan Defense Agency, hosted on Internet Archive, published April 8, 2005,;

Hearing before the Security Committee in the House of Representatives, 162nd Diet (2005) (statement by Ōno Yoshinori, to questions from Representative Shigeki Sato, April 15, 2005),


August 31

North Korea tests the Taepodong-1 medium-range ballistic missile for the first time (traversing over Japan into the Pacific Ocean).




The Liberal Democratic Party (LDP) creates a crisis management project team, led by former Defense Agency chief Nukaga Fukushirō, to consider countermeasures for a possible second missile launch by North Korea. The team debates the possible role of Japanese offensive strike capability but does not recommend a policy change on that point.

Kyodo News, “LDP sets up crisis management project team,” January 27, 1999.

Photo by Joe Jones

JDA Director General Moriya Takemasa

Security Committee in the House of Councillors
February 9

After North Korea’s 1998 Taepodong-1 test, the Diet renewed debate on enemy base strikes, with February discussions bringing a sharper focus on the limitations of such strike capabilities. In answering questions posed by opposition member Maehara Seiji on reconciling strike capabilities with Japan’s spirit of “nonaggression,” various speakers, including Moriya, reaffirmed that any base strike capabilities must be limited such that Japan cannot inflict “catastrophic” or devastating damage on any country. This reaffirmed Japan’s nonaggressive focus on self-defense in the face of new technological threats.

“According to our nation’s interpretation of self-defense capabilities, the constitution does not allow our nation to possess weapons that are devoted to causing catastrophic damage to another country, and this has been stated many times over in the Diet.”
Citation: Hearing before the Security Committee in the House of Representatives, 145th Diet (1999) (statement by JDA Director General Moriya Takemasa, February 9, 1999),

JDA Director General Norota Hōsei

National Security Committee in the House of Representatives
March 3

At this pivotal moment after North Korea’s test, Norota seems to adjust the “imminent danger” clause of the 1956 statement by interpreting an “armed attack” against Japan as beginning at the moment when an aggressor nation “undertakes” (chyakushu) an attack. This might permit Japan to use force before receiving damage from an aggressor, although the “no other measures” limitation still applies. While he addresses the issue of striking enemy aircraft or warships in this quote, later in the Diet hearing he confirms that this interpretation of “imminent danger” also applies to enemy missile base strikes.

“We interpret the case of ‘imminent danger of illegal invasion to our country’ traditionally as when an armed attack breaks out against our country, and we interpret ‘an armed attack breaking out’ not as when we are in danger of being attacked nor when we have actually received damage from an attack, but as when an aggressor nation has started to launch an armed attack against our country. . . . So even when damage has yet to occur in our country, if an aggressor nation undertakes the use of military force, it can be thought that an armed attack has started against our country—and in the event that the two other requirements for invoking self-defense rights are satisfied, it becomes constitutional for our country to invoke those self-defense rights and attack the other nation’s fighter aircrafts and warships.”
Citation: Hearing before the National Security Committee in the House of Representatives, 145th Diet (1999) (statement by JDA Director General Norota Hōsei, March 3, 1999),

JDA Director General Norota Hōsei

Budget Committee in the House of Councillors
March 16

In the context of the strike capabilities debate, Norota explicitly differentiates between preemptive attacks and enemy base strikes for self-defense, in order to emphasize the constitutional limitations of such capabilities.

“I have stated that because a preemptive attack is when another country is attacked in cases when it is inferred that there is a danger of an armed attack [against us], our country’s constitution will not allow such an attack.”
Citation: Hearing before the Budget Committee in the House of Councillors, 145th Diet (1999) (statement by JDA Director General Norota Hōsei, March 16, 1999),


January 11

North Korea withdraws from the Nuclear Non-Proliferation Treaty, while resuming short-range missile testing in February and March.

Citation: Kelsey Davenport, “Chronology of U.S.-North Korean Nuclear and Missile Diplomacy,” Arms Control Association, July 2017,

JDA Director General Ishiba Shigeru

Budget Committee in the House of Representatives
January 24

Building from Norota’s 1999 statements, Ishiba presents a hypothetical situation that could meet the conditions for a constitutionally legal act of self-defense vis-à-vis enemy base strikes. In the scenario, Ishiba argues that if North Korea raised a missile on a launch pad while declaring an intent to attack Tokyo, Japan could interpret the situation as North Korea having started to launch an attack—thus under the Hatoyama interpretation, Japan could strike North Korea’s missiles at-launch, before Japan received damage. Note that later, as North Korea continued to improve its missile technology, this hypothetical is quietly discarded in favor of a hypothetical where Japan counterattacks North Korea only after being struck by a first wave of missiles.

“In short . . . imagine if every possible diplomatic effort has been used to avoid such a situation, but unfortunately such a situation becomes reality.

If North Korea both declares that it will turn Tokyo into ashes and raises a missile, I believe that counts as starting to launch [an attack]. I believe this situation can be understood under international law in this manner as well.”

Citation: Hearing before the Budget Committee in the House of Representatives, 156th Diet (2003) (statement by Minister of State for Defense Ishiba Shigeru, January 24, 2003),

Representative Maehara Seiji

Budget Committee in the House of Representatives
March 3

Maehara questions the contemporary “shield and spear” role division between the United States and Japan, earlier noting how despite the Hatoyama statement, Japan continues to be exclusively the shield in the relationship. Raising questions about trust in the U.S.-Japan relationship, Maehara introduces discussion on hedging on the relationship with the “minimum necessary defense capabilities” (saishōgen hitsuyō no bōeiryoku). In particular, he argues that with various new threats (cyber, missile, terror, and so on), the assumptions under the spear and shield system no longer hold, since the system was developed in the Cold War era to fight off land invasions and other outdated threats.

“While enemy base strikes are within the bounds of self-defense and the constitution in the event of a ballistic missile strike—as determined in 1956—the current way of thinking so far is that Japan will rely on the United States based on the U.S.-Japan Security Treaty. . . .

[But] in short, the spear and shield relationship now does not hold.”

Citation: Hearing before the Budget Committee in the House of Representatives, 156th Diet (2003) (statement by Representative Maehara Seiji, March 3, 2003),

Prime Minister Koizumi Junichirō

Written response to House Representative Itō Eisei’s submitted question related to the Cabinet Legislation Bureau’s authority and interpretations on the right to self-defense
July 15

As prime minister, Koizumi reaffirms the existing government interpretation that enemy strike capabilities are compatible with Japan’s traditionally exclusive defense policy. In particular, he defends Ishiba’s answers on striking enemy missile bases “at-launch” as falling within the bounds of the Hatoyama statement.

“The terminology ‘exclusive defense’ is a passive defense strategy posture that captures the spirit of the constitution—such as in situations when we exercise defense capability after having received an armed attack from an enemy in a manner limited to the minimum necessary for self-defense, or also limiting the possession of defense capabilities to the minimum necessary for self-defense—and is our nation’s fundamental defense policy. I acknowledge that this terminology is repeatedly used in Diet discussions.

The government has traditionally made public the opinion that, ‘In the event that an urgent, unjust invasion/violation is carried out against our country, and if this violation is an attack on our country’s soil through guided missiles, I cannot believe that it is the constitution’s intention for us to sit and wait for our own destruction. In such an event, I think that taking the unavoidably minimum measures in order to protect against such attacks—such as attacking missile bases in order to defend against missile attacks if no other measures are available—is legally within the scope of self-defense and should be considered a possibility.’ . . . And Defense Agency Director General Ishiba’s answer in the House of Representatives Budget Committee on January 24, 2003, repeats this traditional opinion. I do not think that this opinion . . . and the “nonaggressive defense policy” way of thinking contradict each other.

The aforementioned exclusive defense policy way of thinking captures the spirit of the constitution, and the government is not considering changing this.”


Citation: Koizumi Junichirō, “Sending a Written Reponses for the Inquires Submitted by Representative Esei Itō on the Cabinet Legislation Bureau’s Authority and Interpretations Right to Self-defense,” House of Representatives, July 15, 2003,

JDA Director General Ishiba Shigeru

Interview with the Independent in London
September 14

In an English-language interview, Ishiba confirms that Japan has the constitutional right to attack missile sites at-launch, before Japan receives any damage. Still, this only addresses the “imminent illegal” attack on Japan condition and not the “no other measures” for defense or “minimum measures” for defense limitations. On this latter point, Ishiba claimed in 2005 that procuring Tomahawk cruise missiles “may remain within the confines of the minimum necessary force for self-defense” due to their targeting accuracy, and he revealed that the Cabinet Secretariat debated this issue back in 2003 before deciding against pursuing Tomahawk acquisition.

“The Japanese constitution permits my position. Attacking North Korea after a missile attack on Japan is too late. If North Korea orders its military to send a missile to attack Japan and the missile is raised to vertical in preparation for launch, then Japan will assume that an attack has begun and has the right to attack that particular missile launch site. What else can the missile be used for but to attack us?”
Citations: David McNeill, “Japan Warns That It Will Attack if North Korea Aims Missile,” Independent, September 14, 2003,; and
Shimoyachi Nao, “Japan Mulled Buying Cruise Missiles for Pre-emptive Self-Defense: Ishiba,” Japan Times, January 25, 2005,



Prime minister-selected panel recommends consideration for acquisition of strike capabilities.

Citation: David Pilling, “Japan Call to Reshape Defence Capabilities,” Financial Times, October 5, 2004.

JDA Director General Ōno Yoshinori

Security Committee in the House of Representatives
April 15

Ōno emphasizes that regardless of the introduction of ballistic missile defense (BMD) systems to Japan, the legal perspective on enemy base strikes does not change. Ōno touches upon a key dichotomy between what he frames as the legal versus policy differences of enemy base strike capabilities. Beginning with how enemy base strikes have been interpreted as legal, Ōno also highlights the current Japanese policy showing offensive restraint as long as alternative means to addressing conflict exist, such as diplomacy, U.S. intervention, or BMD. Since Japan has always had alternative methods besides enemy base strikes even before BMD, the fundamental interpretation does not change: Japan can legally possess strike capabilities, though operationalizing such systems into policy is an entirely different matter.

“First, I believe this is a question on what exactly can be considered ‘measures’ in terms of [the Hatoyama statement’s clause on] situations where there are no other measures.

I can think of various means that can be considered ‘other measures.’ For example, I believe there is the issue of deciding which other measure to use, such as diplomatic responses, or the issue of role-sharing in the U.S.-Japan alliance system, or [official development assistance]. Among these other options, BMD has recently resulted from progress in science and technology—so how are we to continuing thinking about this matter? Based on this series of events, even up until now we have always had alternative means [from an enemy base strike]. How will we think of this?

I do not fully know whether policy and legal discourses have been confounded or not, in that [some argue] while the legal world permits a strike on enemy bases after a defensive launch order, Japanese policy argues that restraint should be shown in cases where there are other alternative measures. [I cannot confirm] whether Japan has always possessed alternatives [to base strikes, such as diplomacy, U.S.-Japan alliance, and so on], or whether the interpretation [on the constitutionality of striking bases] varies by case.

However, in any case, as I have written here, I think that the issue of a strike against enemy bases after a defense launch order legally does not change. In other words, regardless of the introduction of the BMD system, I believe there is no change in the legal way of thinking related to enemy base strikes, and it follows (and this is a fundamental point), through the appropriate role-sharing between the United States and Japan, Japan has no desire to possess enemy strike capabilities presently—that is what I want to clearly state.”



Citation: Hearing before the Security Committee in the House of Representatives, 162nd Diet (2005) (statement by JDA Director General Ōno Yoshinori, April 15, 2005),

Chief Cabinet Secretary Abe Shinzō

Press conference
July 10

As part of a larger LDP-wide push for more concrete discussions on strike capabilities, then cabinet secretary Abe holds a press conference pushing for the LDP to hold an intra-party study on whether to acquire strike capabilities.

English and Korean language news outlets would later misattribute statements by Foreign Minister Asō Tarō and Nukaga Fukushirō to Abe, reinforcing neighboring nations’ suspicions of Abe’s agenda later when he became prime minister. On July 9, Asō states “if a nuclear-tipped missile approached Japan, there is no way that [Japan] will do nothing until it receives damage,” while Nukaga states “if it is important to defend our citizens, it is reasonable for us as an independent nation to possess limited strike capabilities.”

“It is important that we always consider and research what we should do to protect the nation, Japan’s citizens, and territories. . . . First, we would like to discuss this as a party. . . .

In relation to the constitution, to the extent that there are no other means to defend against a ballistic missile strike, attacking ballistic missile bases is constitutional and within the scope of the right to self-defense. . . . [But] should we have this capability? It is important that we deepen this discussion.”
「日本の国民と国土、国家を守るため何をすべきかとういう視点から、常に検討、研究を行うとは必要ではないか … まず党において議論いただくこともあるかもしれない…

「憲法との関係で、弾道弾などによる攻撃を防ぐために他に手段がないと認められる限りには、誘導弾等の基地をたたくことも法律上、自衛権の範囲内に含まれる … そういう能力を持つべきか。そういう中で議論を深めていく必要がある。」
Citation: “Shift in Administration”: The Trajectory of Abe’s Ascendance to Prime-Minister—Complete Data [in Japanese], (Tokyo: Jiji Press, 2006), 120.


October 9

North Korea tests its first nuclear weapon.


Councillor Tokunaga Hisashi

Accounting Committee in the House of Councillors
April 24

While acknowledging its constitutionality, Councillor Tokunaga describes the technical obstacles that Japan faces in conducting an enemy base strike. In particular, Tokunaga highlights North Korea’s mobile launchers and underground tunnel systems as major barriers to effective strikes, in addition to Japan’s limited intelligence, surveillance, and reconnaissance (ISR) abilities. Tokunaga also argues that the difficulty of differentiating between a regular missile test and a missile aimed at Japan during the “at-launch” stage makes any at-launch enemy base strikes questionable.

“If a situation arises—such as with North Korea—where we can clearly know the location of a missile launch, it may be [legally] valid to do an enemy base strike. However, it is likely that we will not know the precise location because the missile will be loaded on a launcher hidden in mountain tunnels or underground hangars. If we intended to detect [their locations], we would need to use a reconnaissance satellite or unmanned spy plane. And even assuming we properly detect the missile locations, if the enemy states that Japan attacked an ordinary training, it would be difficult to refute such claims. That is to say, despite the legal possibility, I believe in reality it is difficult [to do an enemy base strike].”
Citation: Hearing before the Accounting Committee in the House of Councillors, 171st Diet (2009) (statement by Councillor Tokunaga Hisashi, April 24, 2009),

Prime Minister Asō Tarō

Budgetary Committee in the House of Representatives
May 29

Prime Minister Asō publically pushes for possibly including an official statement on enemy base strike capabilities in the National Defense Program Guidelines (NDPG) revision in 2009. A statement in the NDPG would have opened the doors for an official government study—beyond the intra-party study panels organized by the LDP—and would have been a major step forward for strike capability acquisition.

Asō emphasizes the difference between base strikes and preemptive attacks, while also falling back to the official government stance that Japan currently does not possess strike capabilities and must depend on the U.S.-Japan alliance, reaffirming the importance of the United States in Japan’s defense plans. Asō’s quote below hints at the challenge of the overall strike issue for Japan, as he urges further study.

“I acknowledge that, as we currently continue to revise the NDPG, a discussion is being carried out on whether we should incorporate the possession of so-called ‘enemy base strike capability.’ Currently we have held several meetings related to discussions on security and defense, and received many arguments. I believe that from hereon, there will be many opinions on the NDPG revision put forth, but after seeing these arguments, I think that we need to study this issue again.

[Citing the 1956 statement,] to stay in line with the oft-said, traditional statement, it is essential to differentiate [enemy base strikes] from preemptive strikes in situations when no armed attack is undertaken.

On the other hand . . . because [the Self-Defense Force, or SDF] does not possess force structure intended for enemy base strikes, in relation to this, my fundamental position is that we should preserve Japan’s peace and security by further strengthening the U.S.-Japan security system.”

「[これはずっと昭和三十一年から同じことであります。] 少なくとも、これが従来よく言われるように、武力攻撃を着手していない時点での先制攻撃とは違うというところが一番肝心なところであります。

「 他方。。。敵基地攻撃というものを目的とした装備体系。。。を保有をしておるわけではありませんので、こういったものに関しましては、日米安全保障体制を更にきちんとした上で、我々としては日本の平和と安全を期するということを基本として考えております。」
Citation: Hearing before the Budgetary Committee in the House of Councillors, 171st Diet (2009) (statement by Prime Minister Asō Tarō, May 29, 2009),

The LDP releases draft of its own NDPG


The LDP explicitly supports initiating an official government study on strike capabilities in their proposed version of the NDPG. While acknowledging the importance of the United States’ offensive role in the U.S.-Japan alliance, the LDP draft discusses reevaluating this role-sharing, framing strike capabilities as a credible way to strengthen the allies’ and Japan’s own deterrence. Such language points to how hedging and increased independence act as two factors driving the LDP’s desire for strike capabilities.

“Furthermore, from the viewpoint of strengthening the credibility of allies’ extended deterrence, [we] should initiate a study to quickly achieve a conclusion on the previously constitutionally permitted possession of ‘enemy strategic base strike capabilities’ by the SDF, while taking into account the development and deployment of nuclear and ballistic weapons by neighboring countries.

Currently, while we depend on the United States for strike capabilities, it is necessary to reevaluate the appropriateness of this role-sharing in light of the present security environment and rearrange [it] through [the] guideline consultation. Above all, from the viewpoint of strengthening deterrence capabilities against the ‘missile threat,’ we should initiate a study and quickly reach a conclusion on our country’s possession of an independent strike capability (enemy base strike capability).”
「さらに、同盟国による「拡大抑止」の信頼性を一層強固にする観点から、従 前から法理上は可能とされてきた自衛隊による「策源地攻撃能力」の保持につ いて、周辺国の核兵器・弾道ミサイル等の開発・配備状況も踏まえつつ、検討 を開始し、速やかに結論を得る。(pg. 6)

「現在、打撃力については米国に依存している状態にあるが、このような役割 分担については、現在の安全保障環境に照らしてその適否を再検討し、ガイド ライン協議等を通じ整理する必要がある。 とりわけ「ミサイルの脅威」に対する抑止力を強化する観点から、わが国独 自の打撃力(策源地攻撃能力)の保持について検討を開始し、速やかに結論を 得る。」(pg. 8)
Citation:“Proposal for the Formulation of the New ‘National Defense Program Guidelines’,” Liberal Democratic Party, June 4, 2013,



December 4

The new National Security Council and National Security Secretariat are established.

Officially released NDPG


In contrast with the LDP draft, the official NDPG offers a vaguer recommendation, calling for a general study on ways to respond to the ballistic missile threat without specifying offensive strike. Arguably, the language of the NDPG also deemphasizes the elements of hedging and independent deterrence capabilities, focusing on the importance of the “appropriate” role-sharing between the United States and Japan. The LDP’s more pacifist ruling coalition partner, the New Kōmeitō party, had a role in modifying this language.

“Based on appropriate role- and mission-sharing between Japan and the United States, in order to strengthen the deterrent of the Japan-U.S. alliance as a whole through enhancement of Japan’s own deterrent and response capability, Japan will study a potential form of response capability to address the means of ballistic missile launches and related facilities, and take means as necessary.”
Citation: “National Defense Program Guidelines for FY 2014 and beyond,” Japan Ministry of Defense, December 17, 2013,

Defense Minister Onodera Itsunori and Deputy Chief Cabinet Secretary Mutō Yoshiya

Diplomatic Defense Committee in the House of Councillors
April 1

As Abe and the LDP discuss reinterpreting Article 9 of the Japanese constitution in 2014, various LDP officials seek to clarify that the official government position on enemy base strikes would not change. Drawing from the “three conditions” necessary for use of force under the original Article 9 interpretation, Onodera differentiates preemptive strikes from enemy base strikes by arguing that preemptive strikes fail to fulfill the first condition of “imminent illegal invasion”—wording that is built into the Hatoyama statement on enemy base strikes.

With a backdrop of the 2014 collective self-defense debates, Mutō argues that enemy base strikes fall solely under the provision of individual self-defense, and that no clear geographic limitations have been officially set due to lack of tangible discussion on operationalization. Such language both affirms the LDP’s push for an official study and acknowledges the uncertainties surrounding operationalizing strikes for real threats.

Onodera: “The government has traditionally interpreted that the invocation of the right to self-defense is restricted to situations where the previously discussed ‘three conditions’ apply.

Because the first of the three conditions, of an ‘imminent illegal invasion,’ has been interpreted as when an armed attack has occurred on our country . . . if it means the use of force when there is no armed attack against our country, the first condition [for the right to self-defense] is not satisfied and the action would be interpreted as unconstitutional.”
小野寺五典君: 「政府は従来から、自衛権の発動については、先ほど議論があります三要件があります、この三要件に該当する場合に限られるというふうに解しております。

Mutō: “The current constitutional interpretation recognizes the right to individual self-defense, and there have been no detailed discussions related to its scope.

In general, while the opinion has been expressed that it is not appropriate to geographically limit the activity locations of SDF that exercises individual or collective self-defense, there has been no such discussion on enemy base strikes or the aforementioned preemptive strikes with regard to the scope of individual self-defense.”
武藤義哉: 「個別的自衛権につきましては、現行の憲法解釈上認められているということもありまして、その範囲に関する議論は詳細には行われておりません。一般論として、個別的又は集団的自衛権を行使する自衛隊部隊の活動の場所に地理的な限定を設けることは適切ではないといった意見は表明されておりますけれども、個別的自衛権の範囲に関する御指摘のような敵基地攻撃とかあるいは先ほどのその先制攻撃とか、そういったようなことについては議論をされていないところでございます。」
Citation: Hearing before the Diplomatic Defense Committee in the House of Councillors, 186th Diet (2014) (statements by Defense Minister Onodera Itsunori and Deputy Chief Cabinet Secretary Mutō Yoshiya, April 1, 2014),

Prime Minister Abe Shinzō

Plenary Session of the House of Representatives
April 4

With the NDPG revision coming into effect in 2014, Abe pushes for not only prioritizing improvements on BMD but also introducing an official government study on independent deterrence capabilities, implying enemy base strike capabilities as one of them. In response, several opposition members have cited the 1959 Ino statement on avoiding threatening neighbors, as well as a 1972 prime ministerial statement on “exclusive defense,” as the cornerstone of Japanese policy.

While the new NDPG did encourage a study for a “response capability” against missile threats, Bureau of Defense Policy Director Tokuchi Hideshi later responded in a May 22 Diet session that such an investigation did not necessarily mean base strike capabilities were the only explicit option on the table.

“Based on the progress of North Korea’s ballistic missile capabilities, we have planned in the new defense guidelines to comprehensively improve our nation’s coping capabilities against ballistic missile strikes.

As for response capabilities against ballistic missile launch measures, in order to strengthen the entire U.S.-Japan alliance’s deterrence capabilities that are grounded on the appropriate U.S. role-sharing, it is an important step to conduct a study from the perspective of seeking to strengthen our country’s own deterrence and coping capabilities. Still, at the present time it is undecided whether to allocate funding next year for a study related to this topic.”

Citations: Hearing before the Plenary Session of the House of Councillors, 186th Diet (2014) (statement by Prime Minister Abe Shinzō, April 4, 2014),; and
hearing before the Diplomatic Defense Committee in the House of Councillors, 186th Diet (2014) (statement by Bureau of Defense Policy Director Tokudachi Shuzo, May 22, 2014),

Defense Minister Nakatani Gen

Special Committee on Japan and International Society’s Peace and Security Law in the House of Councillors
August 26

Throughout the security legislation bill debates in the summer of 2015, various Japanese politicians raise the question of how aspects of the new bill concerning the new three conditions for self-defense would impact the strike capabilities debate. While the three new conditions allow for Japan to engage in collective self-defense, Minister Nakatani emphasizes that enemy base strike capabilities fall into the realm of individual self-defense. Other officials, such as Cabinet Legislative Bureau Director Yokobatake Yusuke, confirm on June 3 that even with the constitutionality of enemy base strikes, Japan cannot strike another country under the pretense of collective self-defense.

Additionally, in August 4 and August 24 Diet sessions, Nakatani and Yokobatake reject the notion that Japan has the capabilities to conduct enemy base strikes before an enemy damages Japan, instead emphasizing the prevention of “successive launches” at Japan vis-à-vis enemy base strikes. Thus, the strike debates in 2015 reinforce the official government interpretation expressed by Nakatani on August 26, which again emphasizes the nonpreemptive nature of a hypothetical base strike and the importance of the U.S.-Japan alliance to Japanese security.

“The traditional way of thinking about enemy base strikes does not change under the new three conditions. And while presently this is the case, because there are means such as intercepting oncoming missiles and maintaining the U.S.-Japan security system, currently our country does not possess a force structure designated for striking enemy bases, and also is not hypothesizing a strike on enemy bases—not to mention not hypothesizing an enemy base strike as an exercise of collective self-defense.”
Citations: Hearing before the Special Committee on Japan and International Society’s Peace and Security Law in the House of Councillors, 189th Diet (2015) (statement by Defense Minister Nakatani Gen, August 26, 2015),;
hearing before the Special Committee on Japan and International Society’s Peace and Security Law in the House of Representatives, 189th Diet (2015) (statement by Cabinet Legislative Bureau Director Yokobatake Yusuke, July 3, 2015),;
hearing before the Special Committee on Japan and International Society’s Peace and Security Law in the House of Councillors, 189th Diet (2015) (statement by Defense Minister Nakatani Gen, August 4, 2015),; and
hearing before the Budgetary Committee in the House of Councillors, 189th Diet (2015) (statement by Cabinet Legislative Bureau Director Yokobatake Yusuke, August 24, 2015),
North Korea


September 19

Japan’s Diet passes new “Legislation for Peace and Security,” enabling a wider range of SDF activities in support of foreign forces. It also expands the conditions for the “use of force” to include instances when a foreign country “that is in close relation to Japan” is attacked, so long as there are no other means available, and the use of force is to the minimum extent necessary.

Citation: “Development of Security Legislation,” Ministry of Foreign Affairs of Japan,
North Korea


September 9

North Korea conducts its fifth nuclear weapons test.

Citation: Kelsey Davenport, “Chronology of U.S.-North Korean Nuclear and Missile Diplomacy,” Arms Control Association, July 2017,

LDP panel report on strike capabilities (panel led by Onodera Itsunori)

March 30

The launch of the latest LDP panel on strike capabilities was reported shortly after North Korea’s fifth nuclear test in September 2016, with the public conclusions of the panel being released the following spring. While emphasizing the importance of the U.S.-Japan alliance, the findings also highlight the importance of enemy base strikes. The Japanese and English versions of the findings use the words “counterattack capability” (hangeki nōryoku), placing it in line with the recent emphasis on striking after Japan receives damage from a missile attack. Additionally, the report explicitly mentions cruise missiles as a possible option for strike capabilities. This appears to bear some promise as recent news reports on an official Japanese F-35 study mention possibly acquiring Tomahawk cruise missiles for enemy base strikes.

“Given that the North Korean threats have reached a new level, the government should maintain its fundamental policy of responding to situations by comprehensive measures utilizing the alliance’s force structure. Also, to further enhance deterrence and response capability of the alliance, the government should immediately examine [ways] to possess Japan’s own counterattack capability against adversary bases, including cruise missiles.”
Citations: “Proposal for Immediate and Fundamental Enhancement of Ballistic Missile Defense,” Policy Research Council, Liberal Democratic Party of Japan, March 30, 2017,; and

Prime Minister Abe Shinzō

196th Diet House of Representatives Budget Committee Meeting
February 14

Although Abe does not waver from his promise of maintaining an exclusively defense- oriented security policy, in this budget meeting he highlights the constraints of Japan’s current system. In the context of self-defense, Abe also argues for the legitimacy (and necessity) of acquiring standoff missiles.

“Japan will continue to adhere to an exclusively defense-oriented policy, but at the same time, what I would like the citizens to understand is the reality that exclusive defense is very strict when considered purely as a defense strategy. I would like to say that [an exclusively defense-oriented posture] effectively guarantees a first strike from the opponent, and our country will become a battlefield. In addition, today, defense equipment is very accurate because of precision guidance. It is difficult to avoid this once attacked, so therefore, the reality is that it is much more advantageous to attack beforehand.”
Citation: Hearing before the Budget Committee in the House of Representatives, 196th Diet (2018) (statement by Prime Minister Abe February 14, 2018),¤t=34.

National Defense Program Guidelines

December 18

The latest iteration of Japan’s National Defense Program Guidelines (NDPG) includes plans to enhance “standoff defense capability,” which would allow the Self-Defense Forces to use standoff (long-range) cruise missiles to respond to threats from outside of potential conflict zones (primarily targets in the air or at sea). Although refraining from explicitly mentioning enemy base strike capability, the report also mentions that under the premise of strengthening deterrence the government will continue to review Japan’s attack capability while maintaining the U.S.-Japan basic division of military roles. The new NDPG and Medium-Term Defense Guidelines demonstrated the Abe administration’s commitment to push the boundaries of what kinds of military actions and long-range systems are considered defensive, without making a clear decision on using those systems to strike inside enemy territory.

“[The SDF] will acquire standoff firepower and other requisite capabilities to deal with ships and landing forces attempting to invade Japan, including its remote islands, from outside of the threat zone.”
Citation: “National Defense Program Guidelines for FY 2019 and Beyond,” Japan Ministry of Defense, December 18, 2018,
North Korea


March 11

The Japanese government awards a contract to supply Joint Strike Missiles (JSM) for its fleet of F-35 fighter aircraft to Kongsberg Defense and Aerospace, a Norwegian company. The JSM is a long-range, standoff missile with a range of about 150 nautical miles designed primarily to engage naval and land targets.

Citation: Gabriel Dominguez, “Japan Awards Kongsberg Another Follow-On Contract for Joint Strike Missile,” Janes, December 1, 2020,

Minister of Defense Kōno Tarō

Press Conference at Foreign Correspondent’s Club Japan
July 8

In response to a question about Japan acquiring preemptive strike capability in the wake of abandoning the Aegis Ashore missile defense system, Kono answers in English that he is not sure if the journalist understands “preemptive strike” correctly. A Nikkei article reports that later that day, in a separate television interview, Kono elaborates on his statement and emphasizes that the Japanese government is not considering acquiring preemptive strike capability (the article does not specify whether the second statement was made in Japanese or English).These exchanges highlight how difficult it is to differentiate between “preemptive,” “preventive,” or “first strike” in the context of the enemy base strike capability debate.

“I don’t know if ‘preemptive’ is the right concept. . . . I’m not sure if they are defining the meaning of that word correctly. . . . A lot of people use ‘preemptive strike’ to mean deterrence capability. You need to be careful with using it within the international legal framework. . . . Preemptive strikes violate international law and would never be on the table.”
Citations: Kōno Tarō, “Japan’s National Security in the Post-Corona Era,” The Foreign Correspondent’s Club of Japan, June 25, 2020, Press Conference Video,; Francesca Regalado, “Japan Defense Minister Warns of China Military Intentions in Asia,” Nikkei Asia, June 25, 2020,; and Daishi Abe, “Pacifist Japan Seeks New Name for Defensive Strikes,” Nikkei Asia, July 8, 2020,

Prime Minister Abe Shinzō

198th Diet Plenary Session No. 24 of the House of Representative
May 5

During a Diet plenary session of the House of Representatives, Abe reassures members that discussions surrounding enemy base strike capability have not reached any specific conclusion, despite the adoption of the 2018 NDPG and Medium-Term Defense Guidelines that introduced standoff missiles.

“The government is not considering developing an equipment system for so called enemy base strike attacks, even with the new [defense] guideline and medium-term plans. With regards to the so-called enemy base strike attacks, Japan’s division of roles depends on the strike power of the United States, and we are not currently thinking about changing this fundamental division of roles.”
Citation: Hearing No. 24 before the Plenary Session of the House of Representatives, 198th Diet (2019) (statement by Prime Minister Abe Shinzō, May 5, 2019),
North Korea


August 16

Abe Shinzō officially steps down as prime minister due to health reasons. On the same day, Suga Yoshihide is elected as his replacement by the Diet and is sworn in by Emperor Naruhito at the Imperial Palace. Five days prior to formally leaving his role, Abe urged the government to effectively strengthen missile prevention capability with new policies by the end of 2020, in a subtle push for his successor to help develop a clear policy for “enemy base attack capability” as soon as possible.

Citation: Statement by Prime Minister, September 11, 2020,

Minister of Defense Kishi Nobuo

Post-Cabinet Press Conference
December 18

The National Security Council and the Cabinet reach a decision on the mid-term defense maintenance plan. The plan is threefold: build two new ships for missile defense with Aegis radar systems, continue internal deliberations on strengthening deterrence, and improve standoff missile capability. In the subsequent press conference, Kishi differentiates between standoff missile capability and missile prevention, stressing that standoff missiles will not be used for enemy base attacks and will only be used in the context of Japan’s exclusively defense-oriented policy. This statement comes after consternation among some politicians and media that because standoff missiles have long-range attack capability, even if not used specifically for enemy base attacks, such capability could deviate from exclusive defense.

“I think that it is necessary to differentiate between standoff missiles and the missile prevention measures. With regard to missile prevention, the government is continuing to review/consider it. ”
Citation: Post-Cabinet Press Conference with Minister of Defense, December 18, 2020,

As Japanese leaders perceive their meaning

Enemy base strike capability (teki kichi kōgeki nōryoku, 敵基地攻撃能力): The ability to attack missile launch sites in enemy territory for the purpose of self-defense. As the Hatoyama statement outlines, it is constitutionally permissible only in the face of an “imminent illegal invasion,” when “no other measures” of self-defense are available, and the strike must only use the “minimum measures unavoidable necessary.”

Missile prevention/interdiction capability(misairu soshi nōryoku, ミサイル阻止能力): This is a more recent term that sometimes substitutes for enemy base strike capability, and includes an element of disrupting the potential source of a missile attack. In the 2020 policy recommendations that the LDP proposed on strengthening deterrence, the report refers to missile prevention rather than enemy base strike capability. Alluding to this change, former Minister of Defense Onodera Itsunori wrote in an op-ed that enemy base strike capability carries negative violent connotations, whereas missile prevention more accurately describes the concept of attacking the source of a missile attack, which is not necessarily always an enemy base.

Standoff missile defense capability (sutando ofu misairu bōei nōryoku, スタンドオフミサイル防衛能力): The use of long-range missiles such as the Joint Strike Missile (JSM) that allow the SDF to respond to threats from outside of the enemy’s attacking range, thereby improving the country’s overall exclusively defense-oriented capabilities. Likely targets mentioned include an enemy’s ships, aircraft, or invading forces on Japanese remote islands. Although standoff missiles conceivably could be used against enemy territory for missile prevention, the Japanese government has so-far maintained the stance that they will not be used for such purpose.

Counterattack (hangeki 反撃): An attack made in response to an attack by the enemy

Preemptive strike (sensei kōgeki 先制攻撃): This word carries two distinct meanings. The first relates to instances in which an enemy has already launched an attack against Japan, and in order to mitigate further attacks, Japan can preemptively strike enemy missile launch sites or supporting infrastructure, whether or not those targets were specifically involved in the initial attack on Japan. A second definition is understood as a “first strike,” in which force is used to respond to an anticipated threat that has not yet materialized, which is generally considered illegal under international law and denied as an option by the Japanese government.

Missile defense (misairu bōei, ミサイル防衛): Originally conceived of as simply intercepting missiles that have been launched at Japan (using small missiles to hit the incoming attack at various points of the enemy missile’s trajectory). Also known as Ballistic Missile Defense (BMD).

Comprehensive air and missile defense (sōgō misairu bōkū, 総合ミサイル防空)/Comprehensive Missile Defense Capability (sōgōtekina misairu bōei nōryoku, 総合的なミサイル防衛能力): The formal definition by the Ministry of Defense is “integrated operation of equipment for missile defense and other air defense through a network” for the purpose of improving defense overall. However, as seen in the National Defense Program Guidelines, this expression has also been used to accommodate the future possibility of counter strike or preemptive strike capabilities under the context of strengthening defense and deterrence. In this case, “comprehensive” means the dual use of both BMD and strike capabilities that would allow the SDF to respond more decisively and completely to any threats.

James L. Schoff is a senior fellow in the Carnegie Asia Program. His research focuses on U.S.-Japan relations and regional engagement, Japanese technology innovation, and regional trade and security dynamics.

Hana Anderson is a James C. Gaither Junior Fellow in the Carnegie Asia Program.

David Song was a James C. Gaither Junior Fellow in the Carnegie Asia Program.

In Asia, rapid growth and strong economic fundamentals have lifted hundreds of millions from poverty. But significant cracks have emerged in this hopeful story. Our program recommends policies to manage the growing threats to Asia’s long peace, especially from competition among major powers. We also help decisionmakers address social, institutional, and political obstacles to achieving Asia’s development potential.

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