The U.S. official told CBS News the troop in question was being escorted back to the United States for disciplinary reasons, but after going through airport security, they somehow returned and managed to join the border tour.

“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),” U.N. Command said in its statement earlier. “We believe he is currently in DPRK custody and are working with our KPA counterparts to resolve this incident.” …

A person who said they witnessed the event and was part of the same tour group told CBS News they had just visited one of the buildings at the site when “this man gives out a loud ‘ha ha ha,’ and just runs in between some buildings.”

[The plot thickens. If this is accurate, I wonder just how hard the US will work to get him out. Sounds like he made his choice. — Ed]