Mystery swirls around US soldier who entered North Korea days ago, officials say

Almost 72 hours after 23-year-old U.S. Army Private 2nd Class Travis King entered North Korea, American officials say they have not been able to gain clarity on his location or condition -- and even the circumstances that led him to cross the border remain a mystery.

The Pentagon announced on Thursday that Army counterintelligence officials were investigating what prompted King to separate from a tour group visiting the Demilitarized Zone dividing South and North Korea, where witnesses say he sprinted across the border sometime on Tuesday.

He was originally supposed to fly out of Seoul after being taken to the airport on Monday, officials have said. Back in Texas, he was set to face a "pending administrative separation actions for foreign conviction," one U.S. official has said. He had been in detention for more than a month after an altercation with locals, according to an official.

So far, efforts to gather information have been hamstrung by Pyongyang's stonewalling. Although various agencies and intermediaries have attempted to communicate with the North Korean government about King, none say they have received any response and the country's state media has also remained uncharacteristically silent.

"We're still doing everything we can to try to find out his whereabouts, his well-being and condition and making it clear that we want to see him safely and quickly returned to the United States and to his family," White House spokesman John Kirby said Thursday.