WASHINGTON: The United States warned it could launch a 鈥渕assive military response鈥� to any threats from North Korea following Pyongyang鈥檚 provocative detonation of what it claimed was a miniaturized hydrogen bomb.
Defense Secretary Jim Mattis spoke out on Sunday after North Korea carried out an unexpectedly strong nuclear test, more powerful than the bomb that levelled Hiroshima in 1945.
President Donald Trump called an emergency meeting of his national security advisers and had his second telephone call of the weekend with Japanese Prime Minister Shinzo Abe, but did not talk to South Korea鈥檚 Moon Jae-In 鈥� instead accusing Seoul of 鈥渁ppeasement.鈥�
He threatened drastic economic sanctions, including 鈥渟topping all trade with any country doing business with North Korea.鈥�
US monitors measured a powerful 6.3-magnitude earthquake near the North鈥檚 main testing site on Sunday, felt in parts of China and Russia, with an aftershock possibly caused by a rock collapse.
The North 鈥� which in July carried out two intercontinental ballistic missile (ICBM) launches that apparently brought much of the US mainland into range 鈥� hailed its test of what it described as a hydrogen bomb designed for a rocket as 鈥渁 perfect success.鈥�
Mattis told reporters: 鈥淎ny 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.
鈥淲e are not looking to the total annihilation of a country, namely North Korea,鈥� he added, but warned: 鈥淲e have many options to do so.鈥�
The White House said the US was committed to 鈥渄efending our homeland, territories, and allies using the full range of diplomatic, conventional, and nuclear capabilities at our disposal.鈥�
Pyongyang residents celebrated as a jubilant television newsreader hailed the 鈥渦nprecedentedly large鈥� blast which she said had moved the country closer to 鈥渢he final goal of completing the state nuclear force.鈥�
It prompted an international chorus of condemnation, including from both the North鈥檚 key allies, China and Russia.
UN Secretary General Antonio Guterres condemned the test as 鈥減rofoundly destabilizing.鈥� The Security Council will hold an emergency meeting on Monday.
South Korean President Moon Jae-In, who advocates engagement as well as penalties to bring Pyongyang to the negotiating table, called for new United Nations sanctions to 鈥渃ompletely isolate North Korea.鈥�
On Monday Seoul carried out a live-fire exercise in the Sea of Japan, which it calls the East Sea, using a volley of missiles to simulate an attack on the North鈥檚 nuclear site.
But Trump criticized the US treaty ally on Twitter, saying: 鈥淪outh Korea is finding, as I have told them, that their talk of appeasement with North Korea will not work, they only understand one thing!鈥�
In a statement, the presidential Blue House retorted: 鈥淜orea is a country that experienced a fratricidal war.鈥�
It 鈥渨ill continue to push for the denuclearization of the Korean Peninsula through peaceful means working together with our allies,鈥� it added.
Hours before the test, the North released images of Kim at his country鈥檚 Nuclear Weapons Institute, inspecting a device it called a 鈥渢hermonuclear weapon with super explosive power鈥� entirely made 鈥渂y our own efforts and technology,鈥� according to the Korean Central News Agency.
A series of US and United Nations-backed sanctions seem to have had little effect on Pyongyang.
US Treasury Secretary Steven Mnuchin said Sunday his department was preparing potent new measures that would 鈥渃ut off North Korea economically.鈥�
The measures would ensure that 鈥渁nybody that wants to do trade or business with them will be prevented from doing trade or business with us,鈥� he said on 鈥淔ox News Sunday.鈥�
While the United States has virtually no trade with the North, the burden of such sanctions would fall heavily on China, which buys about 90 percent of North Korean exports.
South Korean experts said the tremor near the North鈥檚 main test site was five to six times stronger than that from a 10-kiloton test a year ago.
Despite fears of a possible radioactive leak, Japanese and Chinese scientists said they had detected no radiation in the atmosphere.
As well as July鈥檚 landmark ICBM tests, Pyongyang last week fired a missile over Japan.
Trump has warned Pyongyang that it faces 鈥渇ire and fury鈥� and that Washington鈥檚 weapons are 鈥渓ocked and loaded.鈥�
But the North has huge artillery forces within range of Seoul, a city of 10 million people, and could inflict mass casualties in retaliation to any strike.
鈥淭here are no realistic military options in terms of striking North Korea, because doing so would likely spark a full-scale war,鈥� Mark Fitzpatrick of the International Institute for Strategic Studies, told AFP.