The U.S. citizen detained in North Korea after crossing the border from South Korea without authorization is an American soldier, according to U.S. officials.

A State Department spokesperson confirmed to The Hill that the U.S. citizen is an American servicemember who willfully crossed into the North Korea border.

Defense Secretary Lloyd Austin said Tuesday that U.S. officials are “working to notify the soldier’s next of kin and engaging to address this incident.”

“We’re very early in this event, and so there’s a lot that that we’re still trying to learn, but what we do know is that one of our service members who was on a tour willfully and without authorization crossed the military demarcation line,” Austin told reporters at the Pentagon.

The United Nations Command, which is led by the U.S. and supervises the area, said earlier Tuesday that officials were working with their North Korean counterparts to resolve the issue. Officials added that the U.S. citizen was on a tour to the Korean border village of Panmunjom in the 154-mile-long Demilitarized Zone (DMZ).  

“A U.S. National on a JSA orientation tour crossed, without authorization, the Military Demarcation Line into the Democratic People’s Republic of Korea (DPRK),” the U.N. Command tweeted.

The U.N. Command and North Korea supervise the area.

Panmunjom is a popular tourist destination and has been used as a neutral location for discussions between the DPRK and South Korea.

The Associated Press contributed.

Updated at 2:23 p.m.