Ko Yun-hwa (L), Administrator of Korea Meteorological Administration, points at where seismic waves observed in South Korea came from, during a media briefing at Korea Meteorological Administration in Seoul, South Korea, January 6, 2016. REUTERS/Kim Hong-Ji TPX IMAGES OF THE DAY

Japan Meteorological Agency's earthquake and tsunami observations division director Yohei Hasegawa points at a graph of ground motion waveform data observed in Japan during a news conference at the Japan Meteorological Agency in Tokyo on implications that an earthquake sourced around North Korea was triggered by an unnatural reason January 6, 2016. North Korea is "likely" to have conducted a nuclear test on Wednesday that caused an earthquake near a known testing site in the isolated country, the South Korean and Japanese governments said. REUTERS/Issei Kato TPX IMAGES OF THE DAY

A sales assistant watches TV sets broadcasting a news report on North Korea's nuclear test, in Seoul, January 6, 2016. REUTERS/Kim Hong-Ji TPX IMAGES OF THE DAY

Hua Chunying, spokeswoman of China's Foreign Ministry, gestures at a regular news conference in Beijing, China, January 6, 2016. China's Foreign Ministry said on Wednesday that Beijing did not have advance knowledge of North Korea's test of a miniaturized hydrogen nuclear device, adding that it firmly opposes Pyongyang's action. REUTERS/Jason Lee TPX IMAGES OF THE DAY

Japan's Prime Minister Shinzo Abe (R) speaks to media after attending a meeting of Security Council of Japan at his official residence in Tokyo February 12, 2013 after reports of North Korea's possible nuclear test. Seismic activities detected at around 0300 GMT in North Korea may be the result of a nuclear test, Japan's top government spokesman said on Tuesday. REUTERS/Issei Kato (JAPAN - Tags: POLITICS MILITARY) 

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) 

Japan Meteorological Agency's earthquake and tsunami observations division director Akira Nagai speaks in front of a monitor showing graphs of ground motion waveform data observed in the morning in Japan during a news conference in Tokyo February 12, 2013. Seismic activities detected at around 0300 GMT in North Korea may be the result of a nuclear test, Japan's top government spokesman said on Tuesday. REUTERS/Toru Hanai (JAPAN - Tags: POLITICS MILITARY) 

Japan Meteorological Agency's earthquake and tsunami observations division director Akira Nagai points to a spot on the map showing the quake centre (X) during a news conference in Tokyo February 12, 2013. Seismic activities detected at around 0300 GMT in North Korea may be the result of a nuclear test, Japan's top government spokesman said on Tuesday. REUTERS/Toru Hanai (JAPAN - Tags: POLITICS MILITARY) 

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) 

Japan Meteorological Agency's earthquake and tsunami observations division director Yasuo Sekita points at a graph of ground motion waveform data observed in the morning in Japan during a news conference in Tokyo on implications that an earthquake sourced around North Korea was triggered by an unnatural reason May 25, 2009. North Korea conducted an underground nuclear test on Monday, stoking tension across the regional economic powerhouse of East Asia and prompting U.N. Security Council members to call an emergency meeting. REUTERS/Yuriko Nakao(JAPAN SCI TECH POLITICS ENVIRONMENT) 

- PHOTO TAKEN 11SEP05 - Satellite image taken on September 11, 2005 shows Yongbyon nuclear reactor, North Korea. North Korea will not give up its nuclear weapons until the United States provides it with civilian atomic reactors, Pyongyang said on September 20, 2005 in a statement that significantly undermined a deal reached just a day earlier.
EDITORIAL USE ONLY 

Workers construct a new nuclear reactor in the North Korean village of
Kumho in this file photo taken August 7, 2002. The United States urged
North Korea December 21, 2002 not to restart a nuclear reactor
suspected of being used to make weapons-grade plutonium. The
International Atomic Energy Agency (IAEA) said that North Korea had
disabled surveillance devices the agency had placed at the
five-megawatt Nyongbyong reactor. REUTERS/Lee Jae-won/File Photo

LJW/RCS/AA 

NORTHKOREA-NUCLEAR/ - Reiussue - Map locating North Korea's nuclear facilities. (SIN01)