wo U.S. servicemen have been arrested in Japan's southern island of Okinawa on suspicion of raping a Japanese woman, police said on Wednesday.

The case comes at a time when Okinawan residents are upset with the Japanese government. The Japanese government allowed a U.S. hybrid aircraft onto the island despite safety concerns to Okinawan residents.

The U.S. ambassador to Japan says the US government is extremely concerned by the incident and supports investigations.

[John Roos, U.S. Ambassador to Japan]:
"This is a very serious matter and it is the full intent of the United States Government to provide full and complete and unequivocal cooperation to the Japanese authorities in their investigation of this matter."

The two U.S. servicemen are suspected of raping the woman early on Tuesday morning in central Okinawa.

Japanese authorities say one of the men has confessed to the rape but the other denies being involved.

The case will likely be handled under Japan's judicial system.

[Osamu Fujimura, Japanese Chief Cabinet Secretary]:
"We've made our views clear to U.S. Ambassador Roos. In addition, both the Okinawan representative of the Defense Ministry and our regional liaison with the U.S. have told the commander of the U.S. forces in Japan that the incident is completely unacceptable. They have strongly requested measures to increase discipline and prevent things like this from happening again."

Japan's Prime Minister also weighed in.

[Yoshihiko Noda, Japanese Prime Minister]:
"This should never have been allowed to happen."

Okinawa is a major center for the U.S. military based in Japan.

Friction over U.S. bases in Okinawa intensified after the 1995 gang rape of a Japanese schoolgirl by U.S. servicemen.

The case sparked widespread protests by Okinawans, who had long resented the American presence due to crime, noise, and deadly accidents.