US President Donald Trump and Japanese Prime Minister Shinzo Abe on Monday condemned North Korea for its “provocative and destabilising” behaviour, after the reclusive nation carried out its biggest nuclear test.

North Korea claimed on Sunday it had successfully tested a hydrogen bomb meant to be loaded onto an intercontinental ballistic missile. It was Pyongyang’s sixth, and the most powerful nuclear test, which was set to raise tension in the region.

The White House said that the two leaders spoke over phone to discuss the North Korean actions as they pledged to continue “close cooperation”.

“The two leaders condemned North Korea’s continued destabilising and provocative actions, confirmed the two countries’ ironclad mutual defence commitments, and pledged to continue close cooperation,” the White House said in a readout of the call.

During the call, Trump reaffirmed the commitment of the United States to defending its homeland, territories, and allies using the full range of diplomatic, conventional, and nuclear capabilities at its disposal.

Earlier in the day, US Defence Secretary James Mattis warned North Korea of “massive military response” to any threats from North Korea.

“We made clear that we have the ability to defend ourselves and our allies, South Korea and Japan, from any attack. And our commitment among the allies is ironclad: Any threat to the United States or its territories, including Guam, or our allies will be met with a massive military response, a response both effective and overwhelming,” Mattis told reporters at the White House.

He made a brief statement to reporters outside the West Wing of the White House after Trump held a meeting with a small group of his national security team.

“We have many military options. The president wanted to be briefed on each one of them,” he said.

“Kim Jong Un should take heed of the United Nations Security Council’s unified voice – all members unanimously agreed on the threat North Korea poses, and remain unanimous in their commitment to the denuclearisation of the Korean peninsula because we are not looking to the total annihilation of a country, namely, North Korea,” Mattis said.

Senator Marco Rubio said North Korea’s threatening actions today are a sober reminder that all nations, including China, must do everything in their power to stop and reverse Pyongyang’s growing nuclear and missile programs.

“We cannot live in a world held hostage by Kim Jong Un’s nuclear blackmail, and I support US-led international efforts to maximise pressure against the North Korean regime and its foreign enablers,” Rubio said.