A US Marine is accused of murdering a woman in Japan. Here’s what you need to know.

A the murder of a woman allegedly committed by a US marine in Okinawa sparked public outrage, prompting the Japanese prime minister to criticize a “heinous crime” and reignited controversy over the heavy military presence on the South Island.

Here are five things to know about the latest affair and Okinawa’s thorny relations with American military bases.

What happened?

Okinawa Prefectural Police said they arrested Lance Cpl. Devin Jacob Ballard, 20, stationed at Futenma Air Base, is suspected of strangling Anna Yagi, 39, at a hotel in Naha, the island’s capital, early Saturday and stealing her wallet and backpack. He denied the allegations, according to Japanese media.

Security camera footage showed a man entering the hotel with the woman and then leaving alone.

Ballard was arrested when a patrolling officer saw him walking later Saturday in an entertainment district in Okinawa City, about 15 miles northeast of Naha. His shaved head and tattoos on his arms matched those of the man in security footage, Kyodo news agency reported.

Why are so many bases concentrated in Okinawa?

Okinawa was under American occupation from World War II until 1972. Today, Okinawa is home to 70% of U.S. military installations and most of the 50,000 U.S. troops based in Japan, although it represents only 0.6% of Japan’s landmass.

In the aftermath of World War II, Japan regained sovereignty under the 1952 San Francisco Peace Treaty, but Okinawa remained under American control, making it a hub for American military buildup.

The return of Okinawa’s sovereignty to Japan in 1972 did little to diminish the number of U.S. bases on the island, leading to the disproportionate burden it faces today.

Why is this so controversial?

There has been anger over rising crime linked to the U.S. military on the island. The number of criminal cases linked to the U.S. military rose to 101 last year, compared to about 40 in 2020, according to prefectural police.

The strong American presence has led to a host of problems, from helicopter crashes to noise pollution. crimes involving military personnelincluding the 1995 gang rape of a 12-year-old local schoolgirl.

This rape by three American soldiers in Okinawa fueled widespread calls to rethink a 1960 pact that defined the legal status of American military personnel based in Japan.

The latest incident has sparked widespread anger.

“I am outraged and stunned to learn that a suspect came to (the entertainment zone) after committing a murder,” Kenji Higa, who lives in Okinawa City, told the Okinawa Times.

Okinawans have long opposed the heavy U.S. military presence on the island, but some have come to understand its strategic value because of what is widely seen as a growing threat from China.

Some also say military bases create jobs and help boost Okinawa’s local economy, accounting for about 5 percent of the region’s annual income.

How does the jurisdiction work?

The 1960 Status of Japanese Forces Agreement is often accused of making U.S. military bases virtually extraterritorial and immune from Japanese domestic laws.

For example, Japanese authorities are struggling to conduct an on-site investigation into alleged environmental pollution inside bases and to regulate low-altitude flights of their planes.

One of the most controversial cases is Japan’s lack of primary jurisdiction over crimes committed by U.S. military personnel in the line of duty.

Even if the crimes are committed while off duty, as long as the individual responsible remains on base, their custody will not be released to Japan until they are charged, according to the Japan Federation of Bar Associations.

In this case, Kyodo reported that a police officer questioned and arrested the suspect while he was walking alone on a street in the Naha entertainment district on Saturday evening.

Japanese prosecutors on Monday began reviewing the suspect’s case to determine whether to file formal charges in the coming weeks.

If convicted, he faces life in prison or the death penalty.

How sensitive is the issue for Japan?

Despite the controversy, Japan — which has a pacifist constitution — is relying on U.S. military power to deter any potential attacks, emphasizing the importance of U.S. soldiers being trained and available 24/7.

But Japan’s security is not necessarily America’s only concern.

Experts say Washington essentially views Okinawa as its strategic fulcrum for military deployment in the region and beyond, and that the island is seen by both countries as important for surveillance of China, the Taiwan Strait and the Korean Peninsula.

In the past, American troops were mobilized from Okinawa to participate in conflicts such as the Gulf War in 1990 and the Iraq War in 2003.