North Korea claimed Wednesday it had successfully tested a hydrogen bomb earlier in the day, swiftly drawing international condemnation.
Pyongyang’s state-run KCNA made a noon announcement that was also broadcast in South Korea, stating that the historic test had been carried out at 10 a.m. local time (0100GMT) under the orders of leader Kim Jong-un -- who last month warned for the first time that his country was "ready to detonate a self-reliant H-bomb.”
Hydrogen bombs involve both fission and fusion reactions to generate even more power than single-stage atomic weapons.
Seoul’s presidential office described what would be North Korea’s fourth ever nuclear test as “a clear violation” of United Nations Security Council (UNSC) resolutions.
Deputy chief of national security Cho Tae-yong added that the South would work with other nations to do everything possible to punish Pyongyang.
North Korea has repeatedly faced sanctions for what its neighbor sees as past provocations, including its last nuclear test in 2013, which prompted months of high tensions on the Korean Peninsula.
Meanwhile in the United States, the White House was cautiously monitoring North Korea’s announcement.
“While we cannot confirm these claims at this time, we condemn any violation of UNSC Resolutions,” said a spokesperson.
In the absence of independent verification, global observers did note what appeared to be an artificial earthquake Wednesday morning in the same region as the North's Punggye-ri test site.
The U.S. Geological Survey recorded the magnitude of the tremor at 5.1.
China, which also reported the seismic activity, had not been informed of the test by its traditional ally North Korea according to the South’s National Intelligence Service, as cited by local news agency Yonhap.
Beijing has been seen to be putting more pressure on Pyongyang to abandon its nuclear weapon ambitions in recent years.
The KCNA’s boast that North Korea had “proudly joined the advanced ranks of nuclear weapons states” also came ahead of Kim Jong-un’s birthday this Friday.
Phil Robertson, Deputy Asia Director from Human Rights Watch, was keen to prevent the authoritarian leader from diverting attention away from humanitarian concerns.
"Kim Jong-Un may think it appropriate to celebrate his birthday early with a nuclear test, but even a hydrogen bomb should not cause the world to forget that the Kim family's hereditary dictatorship is built on the systematic brutalization and abuse of the North Korean people," Robertson said in a statement sent to Anadolu Agency.
The North Korean leader's birthday is on Jan. 8
"The only birthday present that Kim Jong-Un should get from the international community is a one way trip to the International Criminal Court in The Hague, where he should be put on trial for crimes against humanity."