A U.S. Air Force U-2 spy plane on a training flight takes off from Osan Air Base, south of Seoul, on Thursday, Feb. 16, 2012. The Cold War-era aircraft has been one of Washington's only reliable windows into military movements inside North Korea for more than 35 years. (AP Photo/Lee Jin-man)

Photo by: Lee Jin-man

A U.S. Air Force U-2 spy plane on a training flight takes off from Osan Air Base, south of Seoul, on Thursday, Feb. 16, 2012. The Cold War-era aircraft has been one of Washington's only reliable windows into military movements inside North Korea for more than 35 years. (AP Photo/Lee Jin-man)