South Korean soldiers check military fences as they patrol near the demilitarized zone separating North Korea from South Korea, in Paju, north of Seoul February 12, 2013. North Korea conducted its third nuclear test on Tuesday in defiance of U.N. resolutions, angering the United States and Japan and prompting its only major ally, China, to call for calm. REUTERS/Lee Jae-Won (SOUTH KOREA - Tags: MILITARY POLITICS)