A Japanese court on Friday convicted a U.S. sailor of killing a Japanese woman during a robbery near Tokyo and sentenced him to life in prison.

William Reese, 22, was convicted of robbing and fatally beating the 56-year-old woman near the U.S. Navy base in Yokosuka, southwest of Tokyo, on Jan. 3.

The Yokohama District Court sentenced Reese to life in prison, according to court official Atsushi Yajima.

Reese pleaded guilty but said he had not intended to kill the woman, according to Kyodo News agency.

Judge Masazo Ogura said the killing shocked residents near the base and caused them anxiety, Kyodo reported.

Reese, from Pittsgrove, N.J., held the rank of seaman, according to the U.S. Navy in Japan.

The killing rekindled lingering concerns over crime related to the roughly 50,000 U.S. troops stationed in Japan under a mutual security pact.

The concerns boiled over into large protests after three U.S. servicemen raped a schoolgirl on the southern island of Okinawa in 1995, but tensions have cooled in recent years.

The latest case comes at a crucial time for the Japan-U.S. alliance.

In April Japan and the United States agreed on a plan to streamline U.S. forces based in Japan and give Japan's military greater responsibility for security in the region.

The deal includes relocating about 8,000 U.S. Marines from the southern island of Okinawa to the U.S. Pacific island territory of Guam, with Japan shouldering about 60 percent of the nearly $10.3 billion transfer cost.

The plan also would station a U.S. nuclear-powered aircraft carrier in Japan for the first time.