Police officers try to remove demonstrators staging a sit-in protest against the planned deployment of V-22 Ospreay aircraft at Marine Corps Air Station Futenma in Ginowan City, Okinawa, on Sept. 27, 2012. (Kyodo News via Associated Press)

Japanese police have arrested two U.S. sailors in Okinawa on charges of raping a local woman, to which one of the Americans reportedly later confessed. The incident is sadly not the first of its kind on the densely populated Japanese island, where a large U.S. military base houses 15,000 to 20,000 Marines and 10,000 Air Force personnel. The backlash is snowballing in Japan, where the Okinawa base has long been a source of national political controversy, one with larger geopolitical meaning for the United States and Japan.

The Okinawa governor hinted at the potential implications of the alleged rape when he told Japanese media that, in response to the incident, he'd complained directly to the U.S. military, U.S. Consulate and Japanese prime minister's office. For many Okinawans, past crimes by U.S. service members, particularly rapes, have been part of something much larger than just the individual crimes.

Opposition to the U.S. base on Okinawa has been a big deal in Japan for years. "Local newspapers in Okinawa, which are strongly anti-base, give intense coverage to crimes by American military personnel and their families," the New York Times explained. It's also about the base itself, which is in the middle of a dense residential neighborhood and surrounded by schools. The recent arrival of new American aircraft, the tiltrotor V-22 Osprey, which locals believe is too dangerous, provoked "unexpectedly fierce opposition." And maybe it shouldn't be surprising that this historically nationalist society isn't crazy about an enormous foreign military presence on its soil.

Japanese leaders don't have particularly attractive options for addressing the Okinawa issue. In 2010, Japanese Prime Minister Yukio Hatoyama pledged to relocate the U.S. base, then backtracked under U.S. pressure. Outraged Okinawans staged public protests, demonstrations spread to Tokyo, Hatoyama's approval rating plummeted to 25 percent, and he resigned.

Okinawans and Japanese generally were already unhappy about the U.S. base before this week's arrests, so it's not likely that this one incident will on its own change much. But it's easy to see how this could help nudge Japanese politics in a counterproductive direction.

Nationalist politicians are already on the rise, bringing less cooperation and more needless saber-rattling with South Korea and particularly China, with which disputed islands have become a focal point. It was the nationalist governor of Tokyo, Shintaro Ishihara, who provoked China's violently nationalist demonstrations by threatening to buy the disputed Senkaku/Diaoyu islands. It's hard to see how rising nationalism in either Japan or China is particularly helpful for the region's ability to remain stable and cooperative.

If Japanese voters at some point again pressure their leaders to push for moving the base, the United States will have to decide between refusing, thus risking a hit to its relationship with Japan, or acquiescing, which would presumably set back whatever strategic purposes the base serves (containing China? deterring North Korea? securing shipping lanes?). A third option would be for the United States to move its troops some place else, which may inform the thinking behind its just-opened base on Australia's northern coast. 

Whatever the larger political outcome of the incident, it's a reminder of the tension surrounding the American base there that two 23-year-old American sailors can set off a minor international incident.

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