Japan PM protests to US after Marine arrested on murder suspicion in Okinawa

"The occurrence of such an extremely brutal and vicious incident is extremely regrettable," ​Takaichi said in a statement. "The government of Japan strongly protests to the US side ​and strongly seeks maximum cooperation with the investigation," as well as the tightening of discipline and thorough measures to prevent a recurrence, she said.

The US embassy and the Marine Corps expressed condolences ​over the incident and said they were cooperating with the Japanese authorities. The Marines ​said in a statement that the suspect, who is assigned to the III Marine Expeditionary Force ‌and ⁠based at Marine Corps Air Station Futenma, was in Japanese custody.

"The Marine Corps takes these allegations very seriously and expects every Marine to adhere to the highest standards of behavior," it said. Most of the 18,000 Japan-based Marines are stationed in Okinawa, which ​the US held ​from the end ⁠of World War Two until 1972.

Their presence has repeatedly stirred resentment among residents over issues such as noise, aircraft crashes ​and the conduct of personnel. The 1995 rape of a 12-year-old ​Okinawan girl ⁠by three US servicemen sparked mass protests.

Saturday's killing could complicate Takaichi's efforts to relocate some Marines from the busy Futenma air base to a more remote facility at Henoko. Opponents ⁠want ​the troops moved out of the prefecture. Okinawa, which ​is 100 km (60 miles) from Taiwan at the closest point, is viewed by Tokyo and Washington as key ​in deterring potential military aggression from China.