A passenger walks past a television report on North Korea's nuclear test at a railway station in Seoul February 12, 2013. North Korea conducted a nuclear test on Tuesday, South Korea's defence ministry said, after seismic activity measuring 4.9 magnitude was registered by the U.S. Geological Survey. The epicentre of the seismic activity, which was only one km below the Earth's surface, was close to the North's known nuclear test site. REUTERS/Kim Hong-Ji (SOUTH KOREA - Tags: POLITICS TPX IMAGES OF THE DAY)