Over the past several months, North Korea’s hostile rhetoric and its repeated nuclear and missile tests have led to calls for action against the threats posed by its regime. In the United States, the Wall Street Journal has reported (and Professor Victor Cha has hinted) that the Trump administration is considering a so-called “bloody nose” strategy that would “[r]eact to some nuclear or missile test with a targeted strike against a North Korean facility to bloody Pyongyang’s nose and illustrate the high price the regime could pay for its behavior[,]” hopefully without “inciting a full-bore reprisal by North Korea.”
In a recent post here on Lawfare, Lt. Col. Shane Reeves and Capt. Robert Lawless attempted to show that “[t]here is a strong argument such a strike would be lawful.” This in turn triggered vigorous disagreement from several other legal experts, including Professors Kevin Jon Heller, Michael Schmitt, and Ryan Goodman.
One of the topics raised in this debate is how Japan and the United States might respond to the launch of an unarmed North Korean missile into Japanese sovereign territory (e.g., as part of a missile test). Below I offer four observations regarding such a scenario. First, Japan’s views on the right to self-defense under international law make it highly unlikely that it would ever exercise its individual right of self-defense in response to such a development. Second, despite recent arguments to the contrary, the United States cannot exercise collective self-defense with Japan against Japan’s wishes under either customary international law or the 1960 Treaty of Mutual Cooperation and Security between Japan and the United States (i.e., the Japan-U.S. Security Treaty). Third, Japan’s most likely response in such a scenario would be to destroy such a missile, a measure that Japan distinguishes from the use of force as a matter of international law. Finally, Japan should nevertheless prepare for the possibility that the United States will choose to pursue a “bloody nose” strategy under an international law theory of individual self-defense.
Japan’s Approach to Individual Self-Defense
Article 51 of the U.N. Charter makes an “armed attack” the precondition for when a state may exercise its right of individual or collective self-defense. The Japanese government has consistently defined an “armed attack” in this context as meaning “an organized, premeditated use of force against a state.” As “premeditated” suggests, the Japanese government views hostile intent (on the part of North Korea in this case) as the most crucial element in determining the occurrence of an armed attack, not the criteria of scale and effect applied by the International Court of Justice (ICJ) in its Nicaragua decision (though scale and effect may serve as evidence of intent). The Japanese government does not go so far as to say that such intent is a requirement to qualify as an armed attack in a strict legal sense, but it has always referred to an opponent’s subjective intent as the key factor in making an armed attack determination. Further, it has noted that an intent-based armed attack determination is to be made based on “a comprehensive assessment of international affairs, the demonstrated intent of the opponent state, and the means and patterns of attack.” Context thus does matter to Japan in assessing whether there has been an armed attack.
On the other hand, contrary to the views of the United States, the Japanese government has repeatedly rejected the notion that the right to self-defense applies against imminent threats of armed attack. Japan’s longstanding position on the issue is that “the mere likelihood or threat of armed attack does not authorize the exercise of the right to self-defense whatsoever. In other words, neither preemptive strike nor preventive war is permissible.” Hence, Japan is unlikely to respond until it determines that an armed attack has, in fact, occurred.
For these reasons, even if an unarmed missile were to enter Japanese territory as part of a missile test, it seems highly unlikely that the Japanese government would conclude that an armed attack had occurred, at least absent substantial evidence of hostile intent. Instead, Japanese officials would likely evaluate the situation carefully to gauge the level of hostile intent and avoid jumping to any conclusions.
Domestic politics would likely play an important role here as well. A finding that an armed attack had occurred on Japan could prove controversial, as it would be the first such case since World War II. Indeed, Japan has avoided drawing this conclusion in more dramatic circumstances, including a 2004 case in which a nuclear-powered Chinese submarine entered Japanese territorial waters while still submerged, contrary to Article 20 of the U.N. Convention on the Law of the Sea, which both China and Japan have ratified. Thus, in Japan, the threshold for determining there has been an armed attack for Article 51 purposes is quite high in both a legal and a political sense.
The United States and Collective Self-Defense
Japan’s views on individual self-defense in turn set limits on the United States’ ability to act in collective self-defense with Japan. In its Nicaragua judgment, the ICJ established that a declaration of an armed attack and request for assistance by an attacked state are necessary preconditions for an assisting state to exercise any right to collective self-defense with the attacked state. While Reeves and Lawless assert that the Nicaragua judgement is highly debatable, Japan has repeatedly underscored its view that these requirements reflect rules of customary international law. Thus, in its view, Japan must determine that there has been an armed attack and issue a request for assistance before the United States may act pursuant to collective self-defense with Japan.
Professors Aurel Sari and Hitoshi Nasu have argued that the 1960 Japan-U.S. Security Treaty could be read as authorizing the United States to act in collective self-defense with Japan absent any determination, request, or other action by the Japanese government. This argument, however, runs contrary to a host of official statements that Japanese (and American) officials have made since 1960, including in recent debates in the Japanese legislature over North Korean missile tests and joint coordination documents with the United States (as Professor Craig Martin has noted). Japan’s consistent position has instead been that the treaty only authorizes the United States to use force in collective self-defense where Japan exercises its right of individual self-defense in consultation with the United States. This does not alter the customary international law requirements that a victim state first declare an armed attack and request assistance.
Sari and Nasu’s argument is predicated on the fact that Article V of the treaty does not expressly require a request or advance consultation for the exercise of collective self-defense, and that a related 1960 exchange of notes (also available in English) expressly exempts operations conducted under Article V from requirements for “prior consultation” that otherwise apply to major changes in the presence of U.S. troops, equipment, or facilities in Japanese territory or the use of those assets in combat operations. However, their interpretation is untenable for several reasons. First, as Heller and Martin rightly claim, the principle favoring constant bilateral consultation reflected in Article IV of the treaty remains applicable even in the case of U.S. collective self-defense with Japan. Second, such consultation—which serves as an institutionalized platform for the implementation of the treaty, centered on the Japan-U.S. Security Consultative Committee ("2+2")—is supplemental to, and does not supersede, any requirements under international law. This is made clear by Article VII of the treaty which states that the treaty “does not affect and shall not be interpreted as affecting in any way the rights and obligations of the Parties under the Charter of the United Nations[,]” including the preconditions for the exercise of collective self-defense. The proper construction of the treaty therefore should be that, to exercise the right of collective self-defense with Japan, the United States must first receive a request for assistance from Japan following Japan’s own armed attack determination, most likely through the consultation mechanisms established pursuant to the treaty. This is consistent with the manner in which the parties have interpreted and implemented the Japan-U.S. Security Treaty, which requires constant coordination and the joint assessment of situations of concern in order to achieve “seamless, robust, flexible, and effective bilateral responses.”
Japan’s Most Likely Approach: The “Use of Weapons” to Destroy Incoming Projectiles
How then would Japan likely respond if North Korea were to fire an unarmed missile into Japanese territory? Japan has a domestic legal framework for addressing such circumstances, namely the “use of weapons” authority set forth in Articles 82-3 and 93-3 of Japan’s Self-Defense Forces Act. Inserted in 2005 following earlier missile tests by North Korea, this provision authorizes Japan’s Self-Defense Forces (SDF) to respond to “falling objects” such as unidentified missiles, rockets, satellites, and so on by destroying such objects once they enter Japanese territory (or before their entry if they are in the airspace above the high seas, including an exclusive economic zone) using its ballistic missile defense system.
Interestingly, this measure is officially framed by Japan as a “use of weapons,” not a “use of force,” as the latter is only permissible in cases of national self-defense against armed attack under Article 51 of the U.N. Charter. In the Japanese government’s view, the “use of weapons” is not prohibited by the U.N. Charter since it does not amount to a use of force under Article 2(4). Instead, the Japanese government maintains that such actions are consistent with what it maintains is the customary international law right of “minor self-defense” against infringements below the threshold of an armed attack, a right that it maintains is distinct from the right to self-defense against an armed attack set forth in Article 51 of the U.N. Charter. This anomalous interpretation has been criticized by Japanese international law scholars who say that there is no difference between customary international law and the U.N. Charter in relation to the notion of national self-defense. Nonetheless, the Japanese government has advanced this “minor self-defense” right argument for the “use of weapons” under international law for a long time and in a variety of different contexts, such as the protection of its nationals abroad.
Of course, Japan’s “use of weapons” doctrine has limits. It is much more restricted than the use of force and is subject to various domestic laws and regulations defining the nature and scope of SDF operations, particularly as its purpose is only to respond to the infringement at issue. Notably, the “use of weapons” is strictly limited to the destruction of those falling objects alone; Japan cannot counterattack North Korea or its missile sites under this framework. That is the most significant difference between the “use of weapons” in “minor self-defense” against infringements not arising to the level of an armed attack and the use of force in self-defense against armed attacks.
The Relevance of U.S. Individual Self-Defense
Finally, notwithstanding Japan’s ability to destroy any incoming projectiles, retired Major General Charles Dunlap has pointed out that the United States might still be able to use force on the basis of individual self-defense based on its own assessment that the projectile posed an actual or imminent threat of armed attack on the U.S. military forces it maintains Japanese territory. The Japanese government has maintained that whether an armed attack qualifies under Article V of the Japan-U.S. Security Treaty must be determined jointly and any response closely coordinated, as reflected in the bilateral 2015 Guidelines for Japan-U.S. Defense Coordination. If the United States did not coordinate its actions with Japan, the two countries’ anomalous and disparate views on the international law governing the use of force and self-defense—particularly when combined with their potentially different sensitivities and views of the threat level posed by North Korea—could result in a range of very difficult circumstances. For example, if the United States were to pursue a strike in response to an incident in Japanese territory using its forces stationed there, Japan could find itself internationally responsible for aiding and assisting what many view as an illegal use of force by the United States against North Korea. This is particularly relevant to the present situation given the skepticism with which many legal experts view the legality of “bloody nose” strikes. For these reasons, Japan must prepare for the possibility that the United States will act in its own individual self-defense and whatever consequences may flow from that choice.
Further, any U.S. action by U.S. forces stationed in Japanese territory that was not jointly determined to fall under Article V of the Japan-U.S. Security Treaty would still be subject to the “prior consultation” mechanism described above under Article VI of the treaty and the 1960 exchange of notes. Article VI and the exchange of notes add this requirement to the general principle of consultation reflected in Article IV in order to ensure that Japan can avoid becoming embroiled in armed conflicts between the United States and neighboring states (such as China, Russia and North Korea) even where there has been no armed attack on Japan. Indeed, in Japan, this risk has been a source of great concern and controversy since at least the Korean War. And recent discussions surrounding a possible “bloody nose” strike have done little to assuage these concerns.
The opinions expressed here are solely those of the author and do not necessarily represent the position of the Japanese government or the Ministry of Defense of Japan. The English translations of any Japanese texts are the author’s own except where a link to an English translation is provided.