North Korea said it has conducted a hydrogen bomb test in a surprise announcement that caused regional tension and drew swift condemnation from opponents.
If confirmed, the test would be the fourth time Pyongyang has exploded a nuclear device.
South Korean intelligence officials and several analysts, however, reportedly questioned whether Wednesday's explosion was indeed a full-fledged test of a hydrogen device.
There was no radiation detected at Japanese monitoring posts.
Still, before the announcement was made on state television, South Korea's meteorological agency said that a 5.1 magnitude earthquake was detected near a known test site in the secretive and isolated state.
South Korea's presidential office held an emergency meeting and later said that the government would take all possible measures to respond to its neighbour and long-time foe's actions.
READ MORE: Another Korean war is not in the cards
"Our government strongly condemns North Korea ignoring repeated warnings from us and the international community and pushing ahead with the fourth nuclear test, which clearly violated the UN resolutions," Cho Tae-yong, a senior security official at the South Korean presidential office said.
| What exactly are hydrogen bombs? |
Hydrogen bombs are more sophisticated than atomic bombs and can be thousands of times more powerful. With an atomic bomb, uranium or plutonium is split in a process known as nuclear fission. This explosion is used in a hydrogen bomb to trigger a secondary explosion, known as nuclear fusion. Nuclear fusion occurs when lighter elements join together, producing temperatures of up to 400 million Celius and powerful shockwaves. Given the technical challenge of building a H-bomb, one theory is that North Korea may have actually tested a so-called "boosted" bomb. "Boosted" nuclear weapons use a small amount of lithium deuteride to energise the reaction, making them more powerful, but they are not considered full hydrogen explosions. |
The UN Security Council called an emergency meeting for Wednesday, diplomats said, as both neighbouring countries and world powers scrambled to issue stern statements. 유엔 안전보장이사회가 수요일 긴급회의를 소집했고 이웃국가들과 열강들은 앞다투어 단호한 입장의 성명서를 발표했다.
China's foreign ministry said that it had no advance knowledge of any test and that it firmly opposed Pyongyang's action.
Hua Chunying, a ministry spokeswoman, said at a daily news briefing that Beijing - one of North Korea's only allies - would work with the international community on the denuclearisation of the Korean peninsula.
The US government said that it could not confirm a nuclear test but that it would respond appropriately to what it called North Korean "provocations" and that it would continue to protect its allies in the region.
"We have consistently made clear that we will not accept [North Korea] as a nuclear state," a State Department statement said.
Japanese Prime Minister Shinzo Abe called the announcement a threat to his nation's safety.
Abe told reporters: "We absolutely cannot allow this, and condemn it strongly."
READ MORE: What the media gets wrong about North Korea
British Foreign Secretary Philip Hammond said any nuclear test would be a "provocation which I condemn without reservation" and a "grave breach" of UN Security Council resolutions.
The United States Geological Survey (USGS) also detected the quake that South Korea said was 49km (30 miles) from the Punggye-ri site where the North has conducted nuclear tests in the past.
| Was it a hydrogen bomb? |
While the USGS put the depth of the earthquake at 10km, the South Korean agency said it was near the surface. The earthquake was detected just after 10am Seoul time (1am GMT).
Al Jazeera's Adrian Brown, reporting from Beijing, said that North Korea was moving one step nearer to creating a nuclear warhead.
"There will be a good deal of tension once more on the Korean Peninsula today. The big question of course is why North Korea has done this now," he said.
WATCH: Hidden State - Inside North Korea
Brown added the test could partly be seen as a defensive response to US-South Korean military exercises, as well as a reaction to UN sanctions the country is under as a result of for its nuclear and missile programmes. (이번 핵실험은 한미 군사훈련에 대한 방어적 반응이자, 과거 북한의 핵과 미사일 프로그램들에 대해 유엔이 내린 제제에 대한 반응으로 보인다. 이 기사의 핵심논조.)
"When North Korea last tested a nuclear device in 2013, that was as a direct consequence of the sanctions that had been imposed by the United Nations," Brown said. 과거 2013년 북한이 핵장비를 테스트 했었는데, 이 테스트는 유엔이 북한에 부과한 제제에 대한 직접적 반응이었다.
North Korea has so far conducted three nuclear tests - in 2006, 2009 and 2013 - all at Punggye-ri. 북한은 지금까지 2006년, 2009년, 2013년 모든 핵실험을 풍계리에서 행한 바 있다.
The 2013 test registered at 5.1 on the USGS scale. 2013년 핵실험은 (United States Geological Survey 미국 지질 조사소) 규모 5.1이었다.
It is not yet known if Pyongyang has successfully made a nuclear device small enough to be used as a warhead on a ballistic missile, but the likelihood of the isolated country successfully doing so increases with each test. 평양이 성공적으로 탄도미사일의 탄두에 핵장비를 탑재했는지 아직 알 수 없으나, 멀리 떨어진 시골에서 그렇게 성공적으로 핵실험 했을 가능성(공산)은 매번 높아진다.
 |
Source: Al Jazeera and agencies