Mattis warns North Korea of "massive military response"

The US will launch a "massive military response" to any threats from North Korea, Defense Secretary James Mattis said today in a blunt warning to the reclusive nation after it carried out its biggest nuclear test.

North Korea claimed today 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.

"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 a small group of national security members had a meeting today with US President Donald Trump and the Vice President Mike Pence about the latest provocation on the Korean Peninsula.

"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 they remain unanimous on their commitment to the de-nuclearisation of the Korean Peninsula because we are not looking to the total annihilation of a country, namely North Korea. As I said, we have many options to do so," Mattis said.

Mattis' remarks came after  US President Donald Trump warned that "appeasement" won't work with Pyongyang whose "words and actions continue to be very hostile and dangerous" to the US.