By RYO NEMOTO, Nikkei staff writer
TOKYO — When senior officials from Japan’s ruling Liberal Democratic Party met last month to discuss next fiscal year’s defense budget, a former defense minister raised a topic outside the scope of big spending items like missiles and fighter jets.
“We should establish a joint command in Okinawa for the Self-Defense Forces to coordinate with U.S. forces,” the official said.
The former minister’s remark, which comes as Tokyo reviews its national security strategy in the light of a potential Taiwan crisis, points to a challenge beyond hardware, one that is embedded in the U.S.-Japan alliance.
Joint command structures are the norm in other U.S. alliances. American officers serve as top commanders in both NATO — now facing a heightened threat from Russia after Moscow’s invasion of Ukraine — and the U.S.-South Korea alliance. In the latter case, the commander of U.S. forces in South Korea doubles as head of the Combined Forces Command, taking operational control of both militaries in wartime.
Tokyo and Washington have no such unified structure for their seven-decade-old alliance. Under Article 5 of the U.S.-Japan security treaty, the two countries would respond together to any armed attack on territories under Japanese administration. But their forces would operate separately, with their own chains of command.
Revisions to defense cooperation guidelines in 2015 established an Alliance Coordination Mechanism to facilitate diplomatic and defense discussions at multiple levels.
But a framework that works when dealing with a limited threat may falter in a more complicated situation like a conflict over Taiwan. In such a case, on top of actual combat, Tokyo would need to support American forces, defend the nearby Senkaku Islands and evacuate Japanese nationals.
Separate command structures for U.S. and Japanese forces heighten the risk of missteps and could weaken the alliance’s effectiveness as a deterrent against China, critics say.
Japan’s pacifist constitution limits the alliance’s ability to put American and Japanese forces under a NATO-style combined command. Article 9 allows Japan to maintain only the minimum armed forces needed to defend itself. Exercising collective self-defense — coming to the aid of allies — was out of the picture until new national security legislation was passed in 2015.
“The U.S. military’s main alliances involve combined control — the Japan-U.S. alliance is a bit of an outlier,” said Yasuaki Chijiwa, senior fellow at the National Institute for Defense Studies.
“Generally speaking, having a single commander is more efficient. The U.S. military normally sees parallel [chains of command] as something to be avoided,” Chijiwa said.
During past discussions on cooperation guidelines, Washington pushed for the SDF to be placed under the control of an American commander in the event of a conflict, he said.
When considering how Japan should respond to a Taiwan conflict under its constitutional constraints, Bonji Ohara, senior fellow at the Sasakawa Peace Foundation, looks to the SDF’s internal command functions.
“It would be preferable to have a permanent joint command to communicate and conduct joint operations from peacetime on,” Ohara said.
In a conflict, the chief of staff of Japan’s Joint Staff — the SDF’s top uniformed officer — is not only in charge of coordinating Japan’s own response, but also serves as the main point of contact for the chairman of the U.S. Joint Chiefs of Staff, the leader of the Indo-Pacific Command and other American military brass.
A new centralized command structure would enable smoother cooperation with the Americans, proponents say.
The broader regional security picture for Japan is similarly fractured. Alliances in the Indo-Pacific follow a hub-and-spoke model, with the U.S. partnering bilaterally with Japan, South Korea and Australia rather than involving them in a single alliance.
Contrast this with NATO, which responds as one to an attack on any of the bloc’s 30 members — a major reason why Finland and Sweden applied to join after Russia’s invasion of Ukraine.