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YOKOSUKA NAVAL BASE, Japan — The gunmetal-gray ships of the U.S. Navy and the Japanese Self-Defense Forces share the same harbor and train for combat in the same Pacific waters.

Whether they would fight together, if a U.S. ship came under fire, is surprisingly unclear.

Article 9 of the Japanese constitution — a document designed by the United States after WWII to curb any Japanese military ambition — preserves Japan’s right to self-defense of its own ships and territory, yet bars Japan from “collective defense” with other nations.

While that clause has kept Japan out of combat since 1945, it leaves the United States with a troubling uncertainty if one of its ships gets in a fight and needs help from a nearby Japanese vessel.

If Japan’s prime minister could not justify an attack on a U.S. ship as a concurrent threat, Tokyo would face a stark choice: violate its highest law, or risk the fallout of sitting idly by while its closest security ally faces a confrontation at sea.

“Even if a U.S. military ship is attacked in Japanese waters, unless their operation is for the protection of Japan, the SDF cannot provide them with armed support,” said Masahisa Sato, a member of the Japanese Diet’s upper house, and a retired colonel who led Japan’s noncombatant forces into Iraq in 2004.

Japan drew up legislation in 2007 that would have explicitly allowed a ship to defend an ally, but political instability that led to the resignation of three prime ministers in two years killed the measure.

However, recent changes to Japan’s defense posture, borne out of Chinese confrontations and North Korean belligerence, could draw its ships closer to potential conflicts and symbolically further from its antiwar constitution, analysts and lawmakers told Stars and Stripes.

A 10-year defense plan unveiled in December announced that Japan’s newly termed “dynamic defense” would make its force more mobile and ready to respond to regional hot spots. The plan included deploying five more submarines off coastal waters and moving resources closer to the Senkaku Islands, whose ownership is actively disputed by China.

In January, Defense Department Secretary Robert Gates met with Defense Minister Toshimi Kitazawa, who then expressed willingness to strengthen a 1999 law that allows the SDF to provision U.S. ships in case of a security threat to Japan.

Days later, Japanese media widely reported plans later this year for legislation that would allow SDF vessels to supply U.S. ships in international waters during a Korean Peninsula conflict.

The moves suggest to lawmakers in favor of a stronger alliance that Japan is ready to support collective defense when an ally is threatened.

Some analysts, such as former deputy director-general Masataka Suzuki, believe that the spirit of the 1999 law allows Japan broad discretion to defend a U.S. ship, equating an attack on the U.S. in the region as a threat to Japan’s security.

“It is the utmost importance of Japan to avoid a scenario that Japan cannot do anything when U.S. needs Japan’s backup,” said Suzuki, who helped craft the 1999 law.

However, Japanese Prime Minister Naoto Kan and his ruling party have never made as bold a claim as Suzuki suggests, possibly out of a desire to keep Japan’s policy intentionally murky, analysts say.

Opponents of a stronger alliance believe that its backers are overestimating support for Japan’s expanded defense role.

“The Japanese public will never allow a change to the Article 9 provision to make it possible for Japan to attack another country,” said Asaho Mizushima, a constitutional and military law professor at Waseda University. A stronger alliance — especially one with an explicit right to combat — would only provide China with more reason to ratchet up its increasingly assertive military strategy, Mizushima said.

However, Mizushima concedes that alarming changes are under way. The government’s 10-year plan and its successive moves were swiftly made without national debate, he said.

Kan won’t be able to address defense reform at the legislative level until later this year, because he needs support from leftist parties to pass his domestic agenda, said Tsuneo Watanabe, director of foreign and security policy research at the Tokyo Foundation, a think tank.

“Nevertheless, it is necessary for Japan to face the problem at some point,” Watanabe said. “It is a matter of the core of the Japan-U.S. security alliance.”

slavine@pstripes.osd.mil

sumidac@pstripes.osd.mil

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