North Korea said on Jan. 6 it had successfully detonated a hydrogen bomb for the first time.

As officials across the globe immediately moved to condemn the move, some openly doubted Pyongyang's claim.

If the North Korean regime has indeed been able to develop such a thermonuclear weapon, which is hundreds of times more powerful than common nuclear devices, it would mark a tremendous step forward in the hermit kingdom's nuclear capability, The Washington Post reported.

North Korean state-run television made the announcement in a special broadcast from Pyongyang.

"We've carried out a hydrogen bomb test," a spokesperson said. "North Korea was forced to develop its nuclear arsenal because of the U.S.'s hostile policy against North Korea. However, as a peaceful nation and a nuclear powered-nation, North Korea will be a responsible state and will not use its nuclear power before (an attack) and will not transfer the technology to others."

China, France, Japan, the United Kingdom, the United States, the European Union and NATO, among others, sharply condemned the move, The New York Times reported. North Korea is prohibited from conducting any nuclear tests under a series of resolutions the United Nations Security Council has adopted in recent years, the newspaper recalled.

U.N. Secretary General Ban Ki-moon, a South Korean national, called the developments on the Korean peninsula "deeply troubling" in a statement released by his office.

"This act is profoundly destabilising for regional security and seriously undermines international non-proliferation efforts. I condemn it unequivocally," Ban said. "I demand the [Democratic People's Republic of Korea] cease any further nuclear activities and meet its obligations for verifiable denuclearization."

The Department of State, meanwhile, told ABC News it was monitoring the situation.

"We are aware of seismic activity on the Korean Peninsula in the vicinity of a known North Korean nuclear test site and have seen Pyongyang's claims of a nuclear test," said John Kirby, a department spokesman. 

"While we cannot confirm these claims at this time, we condemn any violation of U.N. Security Council Resolutions and again call on North Korea to abide by its international obligations and commitments."