An extra edition of a Japanese newspaper was delivered reporting North Korea's nuclear test, in Tokyo, February 12, 2013.

South Korean protesters burn a North Korean flag following a report of the nuclear test conducted by North Korea, in Seoul, South Korea, February 12, 2013.

Japan Meteorological Agency's earthquake and tsunami observations division director Akira Nagai points to a spot on the map showing the quake center during a news conference in Tokyo, February 12, 2013.

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.

A screen grab of the Nuclear Test Facility site in North Korea, via Google Maps satellite view.

South Korean soldiers monitor computers at the Seoul train station following a report about a possible nuclear test conducted by North Korea, February 12, 2013.

A video grab from KCNA shows the Unha-3 (Milky Way 3) rocket launching at North Korea's West Sea Satellite Launch Site, at the satellite control center in Cholsan county, North Pyongang province December 12, 2012.

North Koreans celebrate the successful launch of the Unha-3 rocket at Kim Il Sung square in Pyongyang December 14, 2012. The sign reads: "Let's glorify dignity and honor of great people of Kim Il Sung and of Korea of Kim Jong Il in the world!"