Japan leader voices outrage over alleged murder by US Marine

A woman's murder allegedly committed by a US Marine in Okinawa is a "heinous crime", Japan's premier said on Monday, as the new accusation of violence involving American forces sparked public outrage.

Crimes including rapes, assaults, hit-and-run and drunk-driving incidents by US personnel have long sparked protests on the island, which bears a disproportionate burden of hosting about 70 percent of US military facilities in Japan.

The new case involves a US Marine stationed on Okinawa who was arrested on suspicion of killing a 39-year-old woman at a hotel in the city of Naha and stealing her wallet, police said on Sunday.

Prime Minister Sanae Takaichi told lawmakers that the government has lodged a strong protest with the United States, urging their "full cooperation with the investigation" and "strict discipline among US military personnel".

"The occurrence of such a heinous crime is extremely regrettable," Takaichi said.

Around 100 people participated in a rally in Naha on Sunday, holding up placards stating their "strong protest" against the murder, Japanese media reported.

Okinawa native Sorane Sakihama, 24, who organised a similar rally in Tokyo on Sunday, said she cried upon learning about the woman's death.

"We couldn't protect her. That made me so angry and sad," the university student told AFP, adding that she was planning to organise another protest in front of the US embassy on Tuesday evening.

"I want to ask them -- what are these soldiers stationed here for? They might say they are here to protect lives or boost security. But how can they say that when a life was taken by their own?"

- 'Extreme disappointment' -

Chief cabinet secretary Minoru Kihara told reporters on Monday that "the government will work with the United States to thoroughly make sure there will be no recurrence, and reduce burdens on local residents".

News of the Marine's arrest immediately prompted Japan's foreign affairs and defence ministers to summon senior US officials to convey their "extreme disappointment" and "lodge strong protests", Kihara said.

The incident came just a few weeks after Okinawa elected Genta Koja as its new governor, ending the eight-year rule of his predecessor who had long pushed for a major US military base to be moved off the island.

Koja, 42, accepts a central government plan to keep the US Marine Corps' Futenma air base on Okinawa's main island, but to move it to a less populated location.

Calling the murder-robbery "extremely malicious in nature", Koja told reporters on Sunday it had "hugely shocked residents here who are forced to live side-by-side with the bases, and instilled new fear in them".

"I am infuriated," Koja said.

He said the incident showed US efforts to "educate soldiers and improve their behaviour have not been functioning at all".

Koja said he will travel to Tokyo "soon" to lodge a protest with top government officials, including Takaichi.

A Japanese court sentenced a US Marine accused of choking and attempting to rape a woman in her 20s to seven years in prison last year.

In 2017, a former US Marine and civilian military base worker was sentenced to life in prison for the rape and murder of a local woman in Okinawa.