SEOUL, South Korea (AP) — North Korea is staying silent about the detention of an American soldier who sprinted across the Koreas’ heavily fortified border as members of his tour group looked on in shock. Some observers say heightened tensions between the two countries make it unlikely that he will return any time soon. Pvt. Travis King bolted into North Korea while on a tour of the Demilitarized Zone on Tuesday, a day after he was supposed to go back to a base in the U.S. He was released from a South Korean prison this month after serving time for assault and was scheduled to return to Fort Bliss, Texas.