A South Korean passenger watches TV news reporting an earthquake in North Korea, at the Seoul train station in Seoul, South Korea, Tuesday, Feb. 12, 2013. The U.S. Geological Survey on Tuesday detected a magnitude 4.9 earthquake in North Korea. Neither Pyongyang nor Seoul confirmed whether North Korea had conducted its widely anticipated third nuclear test, though an analyst in Seoul said a nuclear detonation was a “high possibility.” The Korean letters on the screen read: "North, artificial earthquake 11:58 a.m." (AP Photo/Lee Jin-man)

TOPSHOTS A Chinese national flag flies on a boat before the Sino-Korean Friendship bridge that spans the Yalu River linking the North Korean town of Sinuiju with the Chinese town of Dandong on February 11, 2013. A North Korean state media outlet has accused the United States of "jumping to conclusions" that the North would soon stage a nuclear test, adding to the confusion over its immediate intentions. The US and its ally South Korea are "fussing over speculation" without knowing exactly what action the North plans to take, Tongil Sinbo, a Japan-based pro-North weekly magazine funded by Pyongyang, said. AFP PHOTO/Mark RALSTONMARK RALSTON/AFP/Getty Images

North Korean soldiers stand outside their barracks on the banks of the Yalu River at the North Korean town of Sinuiju on February 11, 2013 across from the Chinese city of Dandong. A North Korean state media outlet has accused the United States of "jumping to conclusions" that the North would soon stage a nuclear test, adding to the confusion over its immediate intentions. The US and its ally South Korea are "fussing over speculation" without knowing exactly what action the North plans to take, Tongil Sinbo, a Japan-based pro-North weekly magazine funded by Pyongyang, said. AFP PHOTO/Mark RALSTONMARK RALSTON/AFP/Getty Images

A South Korean man watches a TV news showing a file footage of North Korea's nuclear test at the Seoul train station in Seoul, South Korea, Tuesday, Feb. 12, 2013. The U.S. Geological Survey on Tuesday detected a magnitude 4.9 earthquake in North Korea. Neither Pyongyang nor Seoul confirmed whether North Korea had conducted its widely anticipated third nuclear test, though an analyst in Seoul said a nuclear detonation was a “high possibility.” (AP Photo/Lee Jin-man)