Charles Jenkins, the U.S. Army sergeant who defected to North Korea in 1965 and was compelled to remain there for almost four decades, has died in Japan at the age of 77.

Mr. Jenkins had been living on Sado Island, off Japan's west coast, with his wife, Hitomi Soga, since he was freed in 2004. A Japanese citizen, Soga had been abducted by North Korea in 1978.

Japan's Kyodo News agency and broadcaster NHK reported his death Tuesday, but the cause was unknown.

Since gaining his freedom, Mr. Jenkins had lived a quiet life on Sado Island, not far from where his wife was taken by the North Koreans, working in the gift shop at the local museum and becoming something of a celebrity. Their 34-year-old daughter, Mika, lives at home and teaches at a nearby kindergarten, while 32-year-old Brinda lives on the closest mainland city, Niigata.

"I'd like to go back to the U.S., but my wife don't want to go, and I have no means to support her there," Mr. Jenkins told the Los Angeles Times in an interview this summer, retaining his thick North Carolina accent. "So I figure, might as well stay where I'm at."

One night in 1965, when he was 24 and serving in the U.S. Army in South Korea, Mr. Jenkins drank 10 beers and stumbled across the world's most heavily militarized border and into North Korea.

"I was so ignorant," he told The Washington Post in an interview in 2008. He had deserted the Army for what became a sentence in a "giant, demented prison."

He was taken into the North Korean system, playing a ruthless American in propaganda movies and teaching English. He memorized the teachings of President Kim Il Sung and killed rats that crawled out of his toilet.

Then in 1980, his North Korean minders brought him a woman who had been kidnapped from Sado Island when she was 18 years old, stuffed in a black body bag and taken by boat to North Korea.

They got married in North Korea and had two daughters who, Mr. Jenkins said in 2008, were in training to become multi­lingual spies for North Korea.

Then, in 2002, under a deal between the Japanese and North Korean governments, Soga was released, along with four other Japanese abductees. In 2004, Mr. Jenkins hobbled off the plane with a walking stick, looking much older than his years, with their daughters.

Later that year, Mr. Jenkins was found guilty of desertion during a court-martial on a U.S. Army base in Japan. He was sentenced to 30 days in prison but was released early.

He told his story in an autobiography, "The Reluctant Communist," released in 2008.

Another American soldier who defected to North Korea died late last year but in Pyongyang.

James Joseph Dresnok, who was 21 when he ran through the demilitarized zone and into North Korea in 1962, died of a stroke at the end of 2016, his two sons said in an interview broadcast in August by the state-run Uriminzokkiri website.