Prime Minister Shinzo Abe on Friday expressed "outrage" after the arrest of a US military base employee linked to the suspicious death of a woman on Okinawa, a week before a high-profile visit to Japan by President Barack Obama.
The southern island was the site of a brutal World War II battle but is now considered a strategic linchpin by hosting numerous US military bases that support the two countries' decades-long security alliance.
"I feel extremely strong outrage," Abe told reporters at his office, calling on the US to take action.
Okinawan police arrested Kenneth Franklin Shinzato for allegedly disposing of the woman's body in a weed-covered area in southern Okinawa, a spokesman told AFP, without elaborating.
Local media said the man, a US citizen and former US Marine, lives in southern Okinawa and works at the US Kadena Air Base.
Police reportedly suspect that the victim, identified as 20-year-old Rina Shimabukuro and who had been missing since late April, was murdered.
Obama is due in Japan next week for a two-day summit of Group of Seven countries which concludes on Friday, before venturing the same day Hiroshima -- becoming the only sitting US president to visit the world's first atomic bombed city.
The Hiroshima visit by Obama, who has a record of calling for global denuclearisation, has been well received in Japan but the issue of the heavy US military presence on Okinawa has long been a periodic thorn in the side of relations.
More than half of the 47,000 US military personnel in the country are stationed there, and rapes and other crimes by service personnel have sparked local protests in the past.
In 1995 the abduction and rape of a 12-year-old girl by three US servicemen sparked massive protests, prompting Washington to pledge efforts to strengthen troop discipline to prevent such crimes and reduce the US footprint on the island.
But continued crimes by American personnel remain a potent rallying point for Okinawans and others in Japan who oppose the presence of the bases on the crowded island, where pacifist sentiment runs high.
Chief Cabinet Secretary and top government spokesman Yoshihide Suga described the recent murder as "abominable" but when asked if Abe would raise it with Obama he said only that the agenda for their talks was still being finalised.
Foreign Minister Fumio Kishida late Thursday summoned US ambassador Caroline Kennedy to lodge a protest, calling the case "very cruel and atrocious".
Kennedy pledged to "cooperate fully with the Okinawa police and Japanese government and redouble our efforts to make sure that this never happens again".
Okinawan Governor Takeshi Onaga, an outspoken critic of the US presence, told reporters Thursday the incident happened "because there are US bases" on the island.
In Washington, officials also spoke out against the incident, with State Department spokesman John Kirby calling it "obviously an outrage."