WASHINGTON - The United States, China and Russia led a chorus of global condemnation Tuesday after North Korea defied months of stark international warnings and carried out a third nuclear test.

President Barack Obama condemned North Korea’s nuclear test Tuesday as a “highly provocative act” that undermines regional stability and said the US would take whatever steps are necessary to defend itself and its allies.

The test, North Korea’s third since 2006, violates numerous United Nations Security Council resolutions and deserves “swift and credible action” from the international community, Obama said in a statement released Tuesday by the White House.

“North Korea’s nuclear weapons and ballistic missile programmes constitute a threat to US national security and to international peace,” he said. “The United States remains vigilant in the face of North Korean provocations and steadfast in our defence commitments to allies in the region.”

The detonation marks an escalation in the global showdown over North Korea’s nuclear programme and threatens to disrupt Obama’s second-term agenda dominated by domestic issues including the economy, gun control and immigration policy. The blast took place as he prepares to give his State of the Union address to a joint session of US Congress Tuesday night.

Obama cited the North Korean missile test as part of a series of threatening actions that isolate North Korea and increase the threat of arms proliferation.

“These provocations do not make North Korea more secure,” the president said. “Far from achieving its stated goal of becoming a strong and prosperous nation, North Korea has instead increasingly isolated and impoverished its people through its ill-advised pursuit of weapons of mass destruction and their means of delivery.”

The US response will pose an early diplomatic challenge to newly installed Secretary of State John Kerry, who last week warned of a “greater potential of conflict” in the event of a North Korean nuclear test.

“The people of North Korea are starving,” Kerry said on Feb. 7 in Washington. “They desperately need to become more open and connected to the world instead of harbouring some of the worst gulags in the world where people are tortured, and forced labour.”

Meanwhile, UN Secretary-General Ban Ki-moon condemned North Korea’s nuclear test on Tuesday as “grave” violation of Security Council resolutions.

“The Secretary-General condemns the underground nuclear weapon test conducted by (North Korea) today,” the secretary-general’s spokesman Martin Nesirky said in a statement. “It is a clear and grave violation of the relevant Security Council resolutions.”

“It is deplorable that Pyongyang defied the strong and unequivocal call from the international community to refrain from any further provocative measures,” Ban, a former South Korean foreign minister, said.

“The Secretary-General is gravely concerned about the negative impact of this deeply destabilizing act on regional stability as well as the global efforts for nuclear non-proliferation.

“The Secretary-General is confident that the Security Council will remain united and take appropriate action. In the meantime, the Secretary-General remains in close contact with all concerned parties and stands ready to assist their efforts,” the statement added.

AFP adds: Japanese Prime Minister Shinzo Abe warned the test was a “grave threat” to his country that “cannot be tolerated,” while Britain called for a “robust response” and Germany said further sanctions should be considered. Even Iran - under harsh UN sanctions over its own controversial nuclear program - used the occasion to call for a nuclear weapons-free world, while defending its own atomic program, which it claims is entirely peaceful. And nuclear-armed Pakistan said it regretted the action. “Pakistan believes that all countries should comply with their respective international obligations,” a spokesman for the foreign ministry said.

The North Korean test came just hours before Obama was to deliver his annual State of the Union address later Tuesday.

The US president called the test a “highly provocative act” that - following the North’s December 12 ballistic missile launch - undermined regional stability and violated UN Security Council resolutions.

“North Korea’s nuclear weapons and ballistic missile programs constitute a threat to US national security and to international peace and security,” Obama said in a statement.

“The danger posed by North Korea’s threatening activities warrants further swift and credible action by the international community,” he said, adding the United States would do whatever was necessary to defend its allies.

The United States, China, Russia and the other major powers face intense pressure to act over North Korea’s defiance of sanctions imposed after previous tests in 2006 and 2009.

North Korea said it staged a successful test of a “miniaturized” bomb, and the US intelligence community said Pyongyang had “probably conducted an underground nuclear explosion” of “approximately several kilotons.” The office of the Director of National Intelligence said it was continuing to analyze the event that happened at the Punggye-ri nuclear test site.

Russian Foreign Minister Sergei Lavrov said he expected the UN Security Council to agree on “an adequate response” to the test. “North Korea should stop its nuclear program and should get back onto the non-proliferation treaty,” Lavrov said. “Then it will stop its international isolation.”

Rounding out the opposition of all five permanent members of the Security Council, France’s President Francois Hollande condemned the blast “in the strongest terms” and said France would back “strong action” by the council.

Canadian Foreign Minister John Baird said the test showed “the North Korean regime’s reckless disregard for the global will” adding it was “unconscionable” that Pyongyang “squanders limited resources” while its people starve. In the Asia-Pacific region, nuclear-armed India called the test a “matter of deep concern,” while Australia, the Philippines and Taiwan condemned the blast.

“The Chinese gave the North Koreans a strong warning against carrying out a test as it became apparent that it was imminent,” said the diplomat, speaking on condition of anonymity. “What the North Koreans have done now is a big challenge to the Chinese,” the diplomat said.

Brazil meanwhile said it was deeply concerned and urged Pyongyang to comply with UN resolutions.