The North's official KCNA news agency said the man was trespassing but gave no further details.
North Korea has been holding another U.S. citizen, activist Robert Park, who was captured in December when he crossed into the communist state saying he planned to raise awareness about its human rights abuses.
In August, former U.S. President Bill Clinton went to North Korea to win the release of two American journalists held by the state for about four months for suspected illegal entry. Clinton's high-profile visit paved the way for direct U.S.-North Korean nuclear talks.
Analysts have said North Korea may try to use Park as a bargaining chip with the United States in high-stakes negotiations over the North's nuclear ambitions.
(Reporting by Jack Kim; Editing by Jonathan Hopfner)