A US serviceman on the Japanese island of Okinawa has been arrested for allegedly molesting a 10-year-old girl.
Armando Valdez, a 27-year-old Air Force sergeant, was detained on Sunday, local police said. He denied the allegations.
Incidents involving US troops and islanders are particularly sensitive because of a 1995 case when three US servicemen raped a schoolgirl.
US forces are to be realigned in Japan, and some Okinawans hope the US presence on their island will be reduced.
But other islanders say the US bases provide welcome jobs and income in what is Japan's poorest prefecture.
According to an official at Okinawa police department, Mr Valdez was arrested on "charges of indecent assault on a 10 year-old girl".
"The suspect allegedly forced the victim to roll her upper clothes up and fondled her breasts," a police spokesman told the French news agency AFP.
A spokesman for the Japanese government, Chief Cabinet Secretary Hiroyuki Hosoda, said he was holding discussions with US officials to ensure such an incident was not repeated.
Okinawa's Governor Keiichi Inamine, who has previously campaigned for a reduction in the number of US troops in the region, said he "can't help concluding there is a problem in the US military's discipline".
Colonel Victor Warzinski, a spokesman for US forces in Japan, said: "We believe this type of alleged behaviour is completely unacceptable."
The United States stations approximately 45,000 troops in Japan, more than half of whom are based on the small island of Okinawa.
The US sees the Okinawa bases, located within striking distance of China and the Korean Peninsula, as essential for its security strategy in Asia and the Pacific region.
But some local residents resent what they see as an unfair burden which the long-standing US-Japan military alliance places on the island.