TOKYO — A United States Navy sailor and a Japanese woman have been found dead on the Japanese island of Okinawa in what the police are investigating as a murder-suicide.
The Japanese Foreign Ministry said in a statement that the sailor appeared to have fatally stabbed the woman and then killed himself with the same knife.
The sailor, 32, and the woman, 44, were found by the Okinawa police on Saturday in an apartment in Chatan, a village on the island’s southwestern coast, according to NHK, the public broadcaster, and the local news media. They have not been publicly identified.
About 25,000 American troops are stationed on Okinawa, half of all American soldiers based in Japan. Violence committed by American service members or related personnel on the island has long caused friction between Washington and Tokyo.
Takeo Akiba, the Japanese vice minister of foreign affairs, protested to William F. Hagerty, the United States ambassador to Japan, in a phone call on Saturday, said Takeshi Osuga, a spokesman for the Foreign Ministry.
Mr. Akiba described the deaths as “extremely regrettable.” According to the Foreign Ministry, Mr. Hagerty said the United States would fully cooperate with the investigation and “do everything we can do to prevent such a case from happening again.”
The police received an urgent call around 7:25 a.m. on Saturday from the father of the dead woman’s young daughter, who was found uninjured in the apartment, said Ichiro Kyan, vice director of the investigation team of the Okinawa Prefectural Police. Mr. Kyan said the police would confirm how the two people died after autopsies were conducted.
“This is an absolute tragedy and we are fully committed to supporting the investigation into the incident,” said First Lt. David Mancilla, a spokesman for the United States Marine Corps in Okinawa. “At this time, the Naval Criminal Investigative Service is in support of the Okinawa Prefectural Police.”
Okinawa residents have protested the heavy presence of United States military forces on the island, and crimes committed by American soldiers or related personnel have ignited deep anger.
In 2017, an Okinawa court sentenced a former United States Marine, Kenneth Franklin Shinzato, to life in prison after convicting him of the rape and murder of Rina Shimabukuro, a 20-year-old Japanese woman.
At the time of the killing, Mr. Shinzato, who served in the Marines from 2007 to 2014, was a civilian working for a contract company on Kadena Air Base, an American military installation on the island.
The relationship between Okinawa, the United States and the government of Japan is fraught. Last year, Denny Tamaki, the son of a Japanese woman and a United States Marine, won a close election for governor of Okinawa in which he opposed plans by Japanese and American officials to transfer a busy Marine air base from one part of the island to another, saying it should be moved out of Okinawa altogether.
The island’s voters rejected the transfer plan in a February referendum, but the central government said construction of the new base would continue.