Chairman of the Joint Chiefs of Staff Gen. Joseph Dunford announced earlier this month that the United States is looking to form a coalition of the willing to patrol the Straits of Hormuz and Bab al-Mandab. According to reports, Japan may be one of the countries to participate. While the Japanese government has so far been reluctant to join, it is worth considering the legality of different potential deployments of the Japanese Self-Defense Forces (SDF) under the existing (internal) legal framework.

Japan’s Constitution, and more specifically its Article 9, does not foresee a Japanese military. In fact, the latter is explicitly prohibited. The official interpretation of the provision however allows for Self-Defense Forces. To reconcile their existence with the Constitution, a number of constraints apply to their equipment as well as to their permissible uses. For instance, an enumerative approach applies to the question of permissible operations: Only where there exists an explicit legal authority in a statute – most importantly, the SDF Act – allowing for the specific use in question may the SDF be deployed. This leads to the coexistence of a variety of legal bases. As we shall see, though, only a handful of them might provide the legal basis for a potential operation in the Strait of Hormuz.

This legal framework provides important context for any plan of a coalition with a potential Japanese participation in mind – and for the Japanese government’s reaction to any such request.

 I. SDF Deployment for Police Measures

1. Anti-Piracy Measures

As a matter of fact, SDF are currently involved in escort activities in the Gulf of Aden, where they have escorted over 3,800 commercial vessels since 2009. The legal basis for this anti-piracy deployment has been Article 82-2 of the SDF Act in conjunction with the so-called Anti-Piracy Act (Act No. 55/2009). This deployment is a police operation in nature (with the Japanese Coast Guard being primarily responsible). If necessary, it may be carried out by SDF, though, which are allowed to use weapons against private actors if needed (according to further provisions of the Act).

However, if such operations – or any other police operation – would be carried out against state actors, these operations would risk amounting to the use of military force in the sense of the prohibition of Article 9 of the Constitution. Therefore, SDF could only be deployed to escort vessels under Article 82-2 SDF Act (and the Anti-Piracy Act) if they were sent to guard ships against private persons operating from a ship – not against agents of a state (nor private persons using aircrafts). When asked after the attack on tankers in the Strait of Hormuz – one of which was operated by a Japanese company – if such a deployment would be possible, Japanese Defense Minister Iwaya stressed that such a deployment would only be considered if the attackers turned out to have been private pirates.

The Anti-Piracy Act may also be insufficient as the basis for a deployment to the Strait of Hormuz for other reasons. Acts of piracy as defined in Article 101 of the U.N. Convention on the Law of the Sea (UNCLOS) and mimicked in Article 2 of the Anti-Piracy Act, are only acts committed on the high seas and (in the Act) on Japanese territorial or internal waters. An international strait in the sense of Article 37 UNCLOS is not the high seas. If littoral states consent to a foreign escort chasing pirates in their territorial or internal waters and/or if the U.N. Security Council authorizes the measures against piracy in the territorial waters of a state as happened in U.N. SC Resolution 1816 of 2008, this does not pose a problem from an international-law point of view. Yet, the applicability of the Japanese Anti-Piracy Act would still be barred, the complications around the scope of Iran’s territorial waters in the Strait of Hormuz notwithstanding.

2. Maritime Security Operation

A similar legal basis that could potentially support a Japanese escort operation can be found in Article 82 of the SDF Act, which allows maritime security operations. This basis would not limit the protection of human life and property against acts of piracy (in fact, before the Anti-Piracy Act was enacted, Anti-Piracy Measures off the coast of Somalia were carried out under this provision, which has since then become subsidiary in cases of piracy). An important difference between the two bases is, however, that unlike the Anti-Piracy Act, Article 82 of the SDF Act focuses on the maintenance of Japanese public order, which means that only vessels with at least some connection to Japan fall under its scope of protection; a scope that seems to align with what the U.S. has in mind. This basis might be the one that comes closest to what the U.S. is asking for.

However, this provision, too, is territorially limited to operations in Japanese waters and Exclusive Economic Zone (EEZ) or on the high seas. Besides, as this operation is in essence a police operation that, in principle, would fall to the Coast Guard (which is reflected in the provisions on the use of weapons), facing state actors could amount to a use of force prohibited under Article 9 of the Constitution. Additionally, in conjunction with certain police operations, the SDF are allowed to provide logistic support to the U.S. military and the military of other states that have concluded an Acquisition and Cross-Servicing Agreement (ACSA) with Japan (Articles 100-6 to 100-15 of the SDF Act); while operations under the Anti-Piracy Act are explicitly mentioned in these provisions, maritime security operations are not.

3. Minesweeping

Another legal basis that allows deployments that are police operations in character is the one for minesweeping, Article 84-2 of the SDF Act. As a police operation, it is again limited to Japanese waters and the high seas – with the protection of Japanese ships in mind. While Japan may have stretched the latter aspect of the provision when it conducted minesweeping activities in the Persian Gulf in 1991, this happened only after the ceasefire was established. Around the Strait of Hormuz, minesweeping would be possible only on the high seas and could only target mines not linked to an ongoing armed conflict.

4. Asset Protection

Finally, Article 95-2 of the SDF Act allows for the protection of weapons and equipment of foreign states. This legal basis is different from the others in that it can be combined with other legal bases. If a foreign state is currently involved in an activity that contributes to the defense of Japan, it may request SDF protection for equipment (such as weapons or ships) that is part of the activity contributing to the defense of Japan. Such protection activities may only be conducted outside areas in which fighting is ongoing and SDF troops must again avoid the risk that their acts might amount to a use of force against a foreign state. They may, however, conduct operations on foreign territory – provided there is consent. Article 95-2 of the SDF Act allows to escort U.S. military vessels and has already been used for such operations.

Commercial vessels may not be protected under this provision. Whether this legal basis could come into play in the present scenario would very much depend on the concrete facts of the situation. Even if the Japanese government was compelled to find a U.S.-led initiative to ensure commercial transit through the strait as an activity contributing to the defense of Japan (in light of the strait’s importance), if U.S. activities were really necessary to ensure safe transit, they would probably be of a military nature. In such a scenario, the likelihood that the strait might see actual fighting is high – and in this case, the SDF would not be able to escort military vessels.

II. SDF Deployment Involving the Use of Force by Japan or Others

The provisions just examined do not allow for a use of force; this limitation applies to the Japanese operations themselves but could also affect potential joint coalition force structures. While it seems likely that Japan would deploy SDF in accordance with this limitation (if at all), one should keep in mind that other, more robust legal bases exist. For argument’s sake, we will look at further provisions that Japan could hypothetically resort to should the situation aggravate.

1. Use of Force by Japan

The most comprehensive legal bases are those authorizing the use of force by Japanese troops themselves. However, due to the aforementioned constitutional constraints, these bases are restricted to individual and – as the result of a controversial governmental reinterpretation of 2014 and the subsequent implementing statutes of 2015 – limited collective self-defense. So far, Japan has never used the SDF based on self-defense. Invoking self-defense would be a far-reaching political decision not likely to be taken absent the direst need. But would it be possible, legally speaking?

Under Article 76 SDF Act, force may be used if three basic conditions are met; the first of which reads as follows:

(1) When an armed attack against Japan has occurred, or when an armed attack against a foreign country that is in a close relationship with Japan occurs and as a result threatens Japan’s survival and poses a clear danger to fundamentally overturn people’s right to life, liberty and pursuit of happiness.

a. Individual Self-Defense

The first condition for individual self-defense is the existence of an armed attack on Japan. Indeed, such could be the case: on June 13, the Kokuka Courageous, a tanker sailing under the flag of Panama but operated by a Japanese company was attacked near the Strait of Hormuz. Several States have blamed Iran to be responsible, which Iran rejected. Japan has so far been – some say uncharacteristically – reluctant to point to an actor responsible for the attack, leaving it open whether it was committed by a State at all. As long as the responsibility has not been established, it will be difficult to consider a potential forcible reaction against Iran; and others have discussed questions of evidence and attribution.

Regarding international law, the International Court of Justice (ICJ) has repeatedly asserted that not every use of force constitutes an armed attack in the sense of Article 51 of the U.N. Charter, which triggers the right to self-defense. While the Court may have left the door open for the possibility that an attack on a commercial vessel may amount to an armed attack in the Oil Platforms Case of 2003, this could only amount to an armed attack on the flag State. In the situation at hand however, the attacked commercial vessel was flying the flag of Panama.

Despite some recent statements that could be understood as indicating the contrary, the Japanese government also holds the view that not every violation of the prohibition on the use of force triggers the right to self-defense, but only “an organized, premeditated use of force against a state.” Accordingly, Japanese Defense Minister Iwaya did not consider the present situation as one of self-defense, stressing that the tanker was no Japanese-flagged ship, no Japanese were aboard, and the crew was not hurt.

b. Limited collective self-defense

On the other hand, the U.S. request could be read as a request for collective self-defense. Potentially, the shootdown of an unmanned U.S. drone by Iran could constitute an armed attack and others have already looked at this incident and examined whether we are in the presence of an armed attack that could support a military response from the U.S.

Even if the armed-attack requirement of international law were fulfilled, this would still not suffice for the first condition for limited collective self-defense in Japanese domestic law to be met, though. Limited collective self-defense is phrased in a way to make it ultimately about the defense of Japan. And, while the condition of a close relationship with Japan is certainly fulfilled by the U.S., Japan does not face a survival-threatening situation (even though a blockage of the oil trade in the Strait of Hormuz was a potential scenario explicitly mentioned in parliamentary debates).

Indeed, without detailing if any of the conditions was fulfilled, Iwaya has already dismissed the situation as one giving rise to a right to collective self-defense for Japan.

c. Deployment Abroad?

If the right to self-defense was triggered, the question of whether SDF would be able to deploy to the Strait of Hormuz would very much depend on what they would be expected to do as, in principle, the SDF are banned from being deployed with the aim of using force on foreign territory with only a few exceptions, minesweeping being the most relevant.

2. Support for Third States Using Force

Finally, instead of using force itself, Japan could send the SDF to support the use of force of other States. For that, the threshold is lower. Still, due to Japan’s constitutional framework, statutes that allow deployments below the threshold of self-defense prohibit the use of force as well as the integration into the use of force of third States (the so-called prohibition of ittaika). In short, this means that SDF activities may not be too closely linked (geographically or with regards to the character of the activity) to the use of force of other States. This may again affect joint coalition force structures and, most importantly, SDF activities may not take place at a location of actual fighting. In 2015, the regulation was relaxed, with permitted activities now including logistical support, search and rescue activities as well as ship-inspection, but no escort missions. While deployment is possible worldwide, activities on the territory of a third state may only be conducted with the consent of said state. Therefore, the most likely scenario on these bases would be logistical support or ship-inspections outside of the strait itself.

Each legal basis in this category comes with its own set of additional requirements that would have to be met. Article 84-5 of the SDF Act in conjunction with the Important Influence Situation Act (Act No. 60/1999), for instance, has developed from the U.S.-Japan cooperation under the U.S.-Japan Security Treaty of 1960. Since 2015, it allows for worldwide deployment in situations that, if left unattended, might amount to an armed attack on Japan. Whether non-military circumstances alone might amount to such an ‘Important Influence Situation’ seems unclear; but given the importance of the Strait of Hormuz for Japan’s energy supply, it seems conceivable that this could be a case in which government would decide it did, if the situation worsened.

As a subsidiary alternative to the Important Influence Situation Act, Article 84-5 of the SDF Act can also be applied in conjunction with the Peace Support Act (Act No. 77/2015). This act would provide similar authority with a different spin: Japanese contribution to international peace and security. This act is the new permanent successor of now-defunct temporary acts that were used to allow for SDF support deployments to Iraq and the Indian Ocean. To be applicable, it would need a resolution of the U.N. Security Council or the General Assembly backing the activities of the States supported by Japan.

IV. Conclusion

This short survey of the potential legal bases that would allow SDF deployment to the Strait of Hormuz (or nearby) shows that the complex Japanese legal framework offers a number of options, all of which come with different caveats and are restricted to specific types of deployment. Much would depend on what the U.S. would ask for. How the Japanese government would respond to such a request may, of course, be as much a political question as a legal one.

The author wishes to thank Prof. Ishii from the National Defense Academy of Japan for her comments on an earlier version of this post. All opinions and errors remain the author’s.

Image: A picture shows the Japanese oil tanker Kokuka Courageous off the port of the Gulf emirate of Fujairah on June 19. Photo: MUMEN KHATIB/AFP/Getty Images