Drawn just below the heavily fortified Demilitarized Zone bisecting the two Koreas, the line strictly controls civilian entry to protect the security of military facilities and operations there, and anyone who crosses it is required to get a prior permit.

In a police probe, the American reportedly stated that he had done the illegal act in the thought that it would contribute to US-North Korea negotiations and subsequently he could attract public attention.

Testifying that he collected information from the Internet for his plan to enter the North, the US national claimed, however, that he had not recognized that crossing the line constitutes a legal violation, according to the police.

He declined to reveal his personal details like his family relations or job, the police said, adding that no problem was found in his health.

The America met a US consul during the probe, the police said.

On Tuesday, the US State Department said that it will visit the US citizen as early as possible and is ready to provide appropriate consular services. (Yonhap)