The U.K. Ministry of Defence has revealed that British troops are training on U.S. military bases in Okinawa. The disclosure, made in response to a request under the U.K. Freedom of Information Act, is the first documentary proof that the U.S. military is using its bases in Japan to train third-country forces, a move that may breach the Japan-U.S. Security Treaty.

According to the Royal Navy Command Headquarters in Portsmouth, England, since January 2015 two Royal Marine lieutenants have been embedded with the U.S. Marines and deployed to U.S. Marine Corps Camp Schwab, in the northern city of Nago, and USMC Camp Hansen, in the central Okinawan town of Kin. While in Okinawa, they have “conducted jungle and range training” in a program approved by the Commandant of the U.S. Marine Corps and the Commandant General Royal Marines.

The 56-year-old Japan-U.S. Security Treaty, under which Pentagon troops are stationed in Japan, does not provide for the training of foreign forces at U.S. bases here. The only exceptions are seven U.S. bases categorized as United Nations Forces installations, but neither Camp Schwab nor Camp Hansen is designated as such.

Okinawa officials reacted angrily to the revelations that the U.S. is training third-country troops in the prefecture. On July 18 a prefecture spokesperson said: “If everybody starts freely using (U.S. bases in Okinawa), there’ll be no stopping it. Whether the Japanese government tacitly gave permission (for this training) or did not know about it, it’s a big problem.”

The following day, Ministry of Defense Press Secretary Hirofumi Takeda appeared to confirm that the deployment violates the Japan-U.S. Security Treaty. “The (treaty) does not allow third-country nationals to use U.S. bases in Japan for training,” he said.

Takeda added that members of foreign militaries are permitted to visit U.S. bases in Japan in an observer capacity provided they follow correct immigration procedures.

However, on Monday, in response to further questioning from Okinawan elected officials Keiko Itokazu and Kantoku Teruya, Cabinet officials appeared to backtrack on Takeda’s statement. They explained that training third-nation forces on Okinawa was not prohibited under the Japan-U.S. Security Treaty and would be decided depending on the circumstances. The spokesperson added that the Japanese government was currently trying to confirm the circumstances of the Royal Marines’ deployment with the British government.

U.S. Forces Japan had not responded to a request for comment in time for publication.

The training of non-U.S. foreign troops in Japan poses potential legal problems. Although U.S. service personnel in Japan are covered by the Japan-U.S. Status of Forces Agreement (SOFA), which exempts them from standard immigration procedures and gives the military primary right of jurisdiction if they break the law while on duty, the agreement does not apply to third-nation forces.

Manabu Sato, a professor of political science at Okinawa International University, said: “It seems U.K. troops in Japan are operating here without legal status. There could be serious ramifications if they were involved in an accident or incident.”

SOFA has recently been under close scrutiny following a spate of crimes involving Americans affiliated with the U.S. military in Okinawa, including the murder of a local resident in April by a former marine. In an attempt to quell public anger, Washington and Tokyo agreed to slightly redefine SOFA to narrow the scope of which civilians would be covered. However, many Okinawan residents continue to demand broader changes that would make U.S. forces fully accountable under Japanese law for crimes committed in the country.

Camp Schwab, where the British troops have been training, is one of the most politically sensitive installations in Japan. As the proposed site for the relocation of the marines’ Futenma air station in Ginowan, it has witnessed mass demonstrations against the plan, and the construction project is currently the focus of an acrimonious court battle between the central government and Okinawa Prefecture.

The training of foreign forces in Okinawa was common between 1945 and 1972, when Okinawa was under U.S. control and the military had free rein in terms of the use of its bases. During the Vietnam War, for example, troops from South Vietnam, South Korea and Thailand were trained in the USMC Northern Training Area (also known as Camp Gonsalves) in the Yanbaru jungle.

In 1971, the Japanese government stated that such training would not be allowed after Okinawa’s reversion to Japanese control. The prefecture was returned to Japan the following year. However, since then, it has long been suspected that the U.S. military was training third-nation troops on the island.

Last year, following the crash of a U.S. Army UH-60 Black Hawk helicopter off the coast of Okinawa, then U.S. Army Chief of Staff Gen. Ray Odierno let slip that the mission had involved “training of special operations forces with several different nations.”

In that instance, the Japanese government declined to confirm the statement.

Jon Mitchell received the inaugural Foreign Correspondents’ Club of Japan Freedom of the Press Award for Lifetime Achievement for his investigations into U.S. military contamination on Okinawa and other base-related problems. Your comments and story ideas: community@japantimes.co.jp