On a large television screen in front of Pyongyang's railway station, a North Korean state television broadcaster announces the news that North Korea conducted a nuclear test on Tuesday, Feb. 12, 2013. North Korea conducted a nuclear test at an underground site in the remote northeast Tuesday, taking an important step toward its goal of building a bomb small enough to be fitted on a missile that could reach United States. (AP Photo/Kim Kwang Hyon)

Photo by: Kim Kwang Hyon

On a large television screen in front of Pyongyang's railway station, a North Korean state television broadcaster announces the news that North Korea conducted a nuclear test on Tuesday, Feb. 12, 2013. North Korea conducted a nuclear test at an underground site in the remote northeast Tuesday, taking an important step toward its goal of building a bomb small enough to be fitted on a missile that could reach United States. (AP Photo/Kim Kwang Hyon)