The United States has made clear its desire to build a coalition for escort operations in the Straits of Hormuz and Bab-el-Mandeb, which officials claim are at risk of Iranian or Iran-backed attacks. The objective of the coalition is twofold: protect commercial assets and bring countries together to counter what Washington has identified as nefarious and escalatory actions by Iran. Reports have emerged that Japan is among the countries the U.S. has eyed for this coalition.

What is Japan’s place in this coalition-building against Iran? The deployment of Self-Defense Forces assets to that area of the world is not unprecedented, but there are two key factors affecting the response that the Japanese government is able and willing to give to the U.S. in this case. The first is the nature of the request to Japan; that is, what type of coalition the U.S. is building and what exactly the U.S. will ask Japan to do. The second is Japan’s broader foreign policy objectives toward Iran, especially the issue of whether Prime Minister Shinzo Abe is still trying to play the role of mediator between the U.S. and Iran.

Right now, it is unclear what Washington will seek from Japan. U.S. officials have suggested that they want a coalition to show multinational support against Iran based on a series of security incidents it has linked to the regime, but there has not been much specificity beyond that. Presumably, the U.S. is simply seeking Maritime Self-Defense Force assets to escort commercial vessels under a U.S.-led coalition, but there is no indication of what force structure or legal mandate would underwrite the operation.

Absent further clarity, there are myriad issues that could factor into Japanese government decision-making, but the two most relevant are legal prohibitions and precedent.

For the SDF, the most significant legal prohibition to any coalition building effort is the principle of ittaika under Japan’s interpretation of Article 9 of the Constitution. This principle mandates that the SDF cannot join a combined command-and-control structure if partner militaries have different rules on “use of force” (i.e., the employment of military capabilities in response to security conflict). As such, the rules of engagement for all partners must be restricted or the SDF cannot legally join the coalition force structure. As a constitutional issue for Japan, this is nonnegotiable. In practice, it means that the U.S.-desired coalition would have to be limited to policing-type actions with restrictions on use of military force if the U.S. wants Japanese participation. It also means that if the situation with Iran escalates further, the SDF would have to leave the coalition.

There is precedent from which to operate. The SDF has participated in Combined Task Force (CTF) 150 and CTF-151 for escort and anti-piracy monitoring missions in the Gulf of Aden. In support of those missions, the MSDF deployed both vessels and aircraft. Japan has kept a constant presence in those CTFs for years, even twice commanding CTF-151. Meanwhile, CTF-152 already operates from the Persian Gulf through the Strait of Hormuz, though Japan has never been a part of it. The existence of these CTFs presents an opportunity in this case.

The U.S. government’s best shot at getting Japan to join its coalition is to build upon precedent. Officials could ask Japan to dedicate MSDF resources to existing CTFs for escort missions in the Straits of Hormuz and Bab-el-Mandeb. Alternatively, the U.S. could create a new CTF under the same Combined Maritime Force structure aimed specifically at what it has deemed as emerging threats in the region tied to Iran. If the request is for an all new coalition and if there are looser restrictions on “use of force,” Tokyo will have to look at other legal frameworks and precedents from which to operate but in the end would likely cite constitutional prohibitions.

Of course, even if the U.S. approaches Japan with the right request, there are still policy issues that may prohibit Japanese involvement. Some observers will rightly note that this is poor timing for Prime Minister Abe and the Liberal Democratic Party-led government ahead of the Upper House election, but more important is that the Abe administration is still weighing its appropriate role in the U.S.-Iran dispute.

Abe volunteered to mediate tensions between the two countries. While his first foray in mediation last month yielded poor results, he has not formally given up on this task. He has been distracted since returning from his Iran trip, staying busy with the Group of 20 summit and the campaign for the Upper House elections. Unfortunately for Abe and his desire to play mediator, Iran was not represented at the G20 and the escalating tension in the Middle East is simply not an important issue for Japanese voters.

The conundrum for Abe is that if Japan sends MSDF vessels to support a U.S.-led coalition, he will lose credibility with Iran, and with it, the ability to mediate. This makes for a big decision for Abe. He may see an SDF deployment as an out, where he can support his U.S. ally while removing himself from the very difficult mediation game. However, he may also see the SDF deployment as potentially escalatory and counterproductive to Japan’s foreign policy interests.

This decision will be debated in various sectors of the Japanese government. The MSDF will consider its resource availability, perhaps needing to draw down commitments elsewhere to transfer assets to the Straits of Hormuz and Bab-el-Mandeb.

The Defense Ministry and the SDF Joint Staff will consider what the scope of operations may be, as well as what rules of engagement could be viable for all of the different scenarios SDF assets could encounter while conducting such missions. The Cabinet Secretariat will be examining legal and policy precedents. The National Security Council and Foreign Ministry will be considering the longer-term foreign policy implications, both for alliance management with the U.S. and for Japan’s Middle East strategy.

As for Abe’s Cabinet and the members of the ruling LDP: They are likely to be split on this. Certainly, some will want to exercise greater presence in global affairs. However, most will want to stick with diplomacy rather than put MSDF vessels in the middle of escalating tensions, especially when Japan’s historical policy for the Middle East has been to play the neutral, de-escalating party.

There is still much internal and intra-alliance debate necessary here, but this much is clear: Japan’s participation in any coalition is far from a foregone conclusion.

Michael MacArthur Bosack is the special adviser for government relations at the Yokosuka Council on Asia-Pacific Studies. He was the deputy chief of government relations at Headquarters, U.S. Forces Japan and is a former officer in the U.S. Air Force.

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