U.S. Secretary of Defense Chuck Hagel made a symbolic visit to the heavily armed truce village bordering North Korea on Monday, stressing its strategic importance in defending the Korean Peninsula. Hagel made the Demilitarized Zone tour his first order of an unprecedentedly longA, four-day visit to the Asian ally ahead of an annual bilateral defenseA summit slated for Wednesday, which is expected to assess the North Korean threat and alliance issues with Seoul.