It has never been easy for the United States to secure the return of citizens from North Korea, one of the world's most isolated nations.

The task may be even harder in the case of Pfc. Travis King, with communication between the countries now almost nonexistent, say diplomats and negotiators.

King, an active-duty U.S. Army soldier serving in South Korea, sprinted into North Korea while on a civilian tour of the Demilitarized Zone on the border between the two Koreas.