Okinawa Prefectural Police arrested a 20-year-old Marine assigned to Futenma Air Station on Okinawa for the alleged murder of a woman in her hotel room in Naha, the island’s capital. The woman was found dead on Saturday morning, and security camera footage showed the suspect entering the room with her and later leaving alone with her belongings, according to Kyodo News and the AFP. The suspect has denied the allegations.

Okinawa Gov. Genta Koja called the case a “major shock” and said it “adds fear to the Okinawans who have already been forced to live next to U.S. bases.” He added, “It is absolutely unforgivable and we are outraged.” Koja criticized the U.S. military, saying, “Discipline and troop education are not working at all.”

Japanese Prime Minister Sanae Takaichi called the crime “exceptionally brutal and vicious” and said the government had lodged a strong protest with the U.S. She demanded “maximum cooperation with the investigation, enforce stricter discipline among U.S. military personnel, and take thorough measures to prevent the recurrence of similar crimes.” Foreign Minister Toshimitsu Motegi summoned U.S. Ambassador George Glass to express “outrage.”

Glass expressed “sincere condolences” to the victim’s family and pledged “full cooperation” with the investigation on social media. The U.S. Marine Corps confirmed the suspect is assigned to the III Marine Expeditionary Force and stated, “The Marine Corps takes these allegations very seriously and expects every Marine to adhere to the highest standards of behavior.”

Okinawa has long been a flashpoint for U.S. military-related crime and local resentment. The island hosts about half of the U.S. military personnel in Japan, with estimates ranging from 50,000 to 54,000 total troops. Last year, more than 100 arrests were made involving U.S. service members and their families. In 2017, a former U.S. Marine was sentenced to life in prison for the rape and murder of a local woman.

The Futenma Air Station, where the suspect was stationed, is located in a densely populated area of Naha and has been a source of local opposition for decades.