The man was arrested Tuesday night at a river near the Korean Demilitarized Zone, part of a restricted military area, said the official, speaking on condition of anonymity due to office policy. He said investigators are questioning the man about the purpose of his apparent attempt to enter North Korea but gave no further details.
Yonhap news agency, citing an unidentified government source, reported the man was in his late 20s or early 30s and told investigators that he tried to go to North Korea to meet leader Kim Jong Un. He was caught by South Korean marines while lying on the shore of the river after swimming north, the report said.
Last year, South Korean soldiers shot and killed a man with a South Korean passport who officials said ignored warnings to return the South after trying to go to North Korea via a river that runs through the border.
There have been occasional cases of Americans being arrested in North Korea after allegedly entering the country illegally from China, but an American trying to go to North Korea from South Korea is unusual.
In 1996, American Evan C. Hunziker entered the North by swimming across the Yalu River, which marks the border with China. Hunziker, who apparently made the swim on a drunken dare, was accused of spying and detained for three months.
Hunziker, then 26, was eventually freed after negotiations involving a special U.S. envoy. The North Koreans wanted to slap Hunziker with a $100,000 criminal fine but eventually agreed on a $5,000 payment to settle a bill for a hotel where he was detained.
North Korea is currently holding three Americans and the country's Supreme Court on Sunday sentenced one of them to six years of hard labor for illegally entering the country to commit espionage.
The Korean Peninsula remains in a technical state of war because the 1950-53 Korean War ended with an armistice, not a peace treaty. About 28,500 U.S. troops are stationed in South Korea to deter potential aggression from North Korea.
About 27,000 North Koreans have defected to South Korea to avoid poverty and political suppression since the end of the Korean War. A few South Koreans have previously tried to defect to the impoverished, authoritarian country, but such cases are rare.
