US warns North Korea of 'massive military response' after nuclear test
US Defence Secretary Jim Mattis has reacted to North Korea's latest nuclear test by saying threats to the United States and its allies "will be met with a massive military response".
Mr Mattis spoke at the White House following a meeting with President Donald Trump and national security advisers. He said any response will be "both effective and overwhelming".
Mr Mattis said the United States is "not looking to the total annihilation" of North Korea, but added "we have many options to do so".
North Korea claimed "perfect success" in an underground test of what it called a hydrogen bomb - potentially vastly more destructive than an atomic bomb.
It was the North's sixth nuclear test since 2006, but the first since Mr Trump took office in January.
In a brief statement to reporters Mr Mattis said the international community was unified in demanding the denuclearisation of the Korean peninsula and said the North's leader, Kim Jong Un, should know that Washington's commitment to Japan and South Korea is unshakeable.
Earlier, Mr Trump raised the stakes in the escalating crisis over North Korea's nuclear threats, suggesting drastic economic measures against China and criticising ally South Korea.
With General Joseph Dunford, chairman of the Joint Chiefs of Staff, at his side, Mr Mattis said: "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."
Those words alone were within the usual bounds of US commentary on answering North Korean aggression. But he seemed to take it a step further with the reference to "total annihilation".
Mr Mattis, who did not take questions from reporters, said he had attended a "small group" national security meeting with Mr Trump and others. He said the president wanted to be briefed on each of what Mr Mattis called "many military options" for action against North Korea.
"We made clear that we have the ability to defend ourselves and our allies, South Korea and Japan, from any attacks, and our commitments among the allies are ironclad," he said.
Mr Trump, asked by a reporter during a trip to church services if he would attack the North, said: "We'll see."
The precise strength of the underground nuclear explosion had yet to be determined. South Korea's weather agency said the artificial earthquake caused by the explosion was five times to six times stronger than tremors generated by the North's previous five tests.
North Korea's state-run television broadcast a special bulletin to announce the test, and said Kim attended a meeting of the ruling party's presidium and signed the go-ahead order.
Earlier, the party's newspaper published photos of Kim examining what it said was a nuclear warhead being fitted onto an intercontinental ballistic missile.
Sunday's detonation builds on recent North Korean advances that include test launches in July of two ICBMs that are believed to be capable of reaching the mainland US.
The North says its missile development is part of a defensive effort to build a viable nuclear deterrent that can target US cities.
The Arms Control Association said the explosion appeared to produce a yield in excess of 100 kilotons of TNT equivalent, which it said strongly suggests the North tested a high-yield but compact nuclear weapon that could be launched on a missile of intermediate or intercontinental range.
Hans Kristensen, a nuclear weapons expert at the Federation of American Scientists, said the North probably will need to do more tests before achieving a functioning hydrogen bomb design.
Beyond the science of the blast, North Korea's accelerating push to field a nuclear weapon that can target all of the United States is creating political complications for the US as it seeks to balance resolve with reassurance to allies that Washington will uphold its decades-long commitment to deter nuclear attack on South Korea and Japan.
That is why some questioned Mr Trump's jab on Sunday at South Korea.
He tweeted that Seoul is finding that its "talk of appeasement" will not work.
The North Koreans, he added, "only understand one thing", implying military force might be required.
The US has about 28,000 troops stationed in South Korea and is obliged by treaty to defend it in the event of war.
Mr Trump also suggested putting more pressure on China, the North's patron for many decades and a vital US trading partner, in hopes of persuading Beijing to exert more effective leverage on its neighbour.
Mr Trump tweeted that the US is considering "stopping all trade with any country doing business with North Korea".
China's official Xinhua News Agency said President Xi Jinping and Russian leader Vladimir Putin, meeting on the sidelines of a Beijing-led economic summit, agreed "to adhere to the goal of the denuclearisation of the Korean Peninsula, have close communication and co-ordination and properly respond" to the test.