TOKYO: The commander of US Forces Japan imposed a night curfew on military personnel on Friday after two US servicemen were arrested on suspicion of raping a Japanese woman on the southern island of Okinawa.

The arrests come at a time when public opinion in Okinawa is at odds with Tokyo for allowing the US deployment of Osprey hybrid aircraft on the island despite lingering concerns about their safety.

Friction over US bases on Okinawa intensified after the 1995 rape of a 12-year-old Japanese schoolgirl by three US servicemen. The case sparked widespread protests by Okinawans, who had long resented the American presence due to crime, noise and deadly accidents.

“I want to personally apologise for the grief and trauma the victim has endured and the anger it has caused among people in Okinawa,” Lieutenant-General Salvatore Angelella told reporters.

“I am immediately issuing a curfew to all military personnel in Japan, both temporary and assigned.”

All personnel will be confined to base from 11 p.m. until 5 a.m. He did not say how long the curfew would be in effect.

The arrests coincide with a sharp deterioration in Japan's relations with China over a disputed East China Sea island chain that makes it strategically important for Tokyo to reaffirm its alliance with the United States.

Japanese Defence Minister Satoshi Morimoto vowed to press the United States on discipline.

Okinawa Governor Hirokazu Nakaima described the rape as “madness”.

The US military said on Thursday it would soon announce measures to ensure responsible behaviour by troops on Okinawa.