United States Vice-President Mike Pence, warning North Korea to give up its nuclear and missile programmes, has promised an "overwhelming and effective" response to any attack on the US or its allies.
"Those who challenge our resolve and our readiness should know we will defeat any attack and meet any use of conventional or nuclear weapons with an overwhelming and effective American response," he said yesterday on board the USS Ronald Reagan aircraft carrier.
Citing the recent US bombings of Syria and Afghanistan, he said: "The shield stands guard and the sword stands ready." He told 2,500 military personnel at the Yokosuka Naval Base, a hub for the US Navy in the western Pacific, that "North Korea is the most dangerous and urgent threat to peace and security in the Asia-Pacific".
Mr Pence left Japan for Indonesia yesterday for the third leg of his 10-day tour of Asia.
Pyongyang, which is intent on building a nuclear-tipped warhead capable of striking the US, unsuccessfully fired a missile on Sunday in what experts posit to be a new weapon that can be used to target ships. Just a day earlier, it had apparently unveiled new missiles at an annual parade. North Korean Vice-Foreign Minister Han Song Ryol told the BBC this week that his country "will be conducting more missile tests on a weekly, monthly and yearly basis", threatening "all-out war" in the event of US military action.
Beijing yesterday said it was seriously concerned by recent comments from Pyongyang. Chinese Foreign Ministry spokesman Lu Kang said China was "resolutely opposed to any words or actions" that might further raise tensions.
Mr Pence vowed to put "economic and diplomatic pressure" on Pyongyang, with "all options on the table".
He said despite more than two decades of efforts by the US and its allies to peacefully dismantle the North's weapon programme, "at every step of the way, North Korea answered our overtures with wilful deception, broken promises and nuclear and missile tests".
He also alluded to tensions in the South China Sea, where China is embroiled in territorial rows with several South-east Asian countries, saying the US will stoutly defend the freedom of navigation through the waterway.
He added that the US' treaty with Japan "covers all the territory administered by Japan, including the Senkaku Islands" - disputed islands in the East China Sea controlled by Japan but claimed by China, which calls them Diaoyu Islands.
The US will deploy 60 per cent of its naval fleet to the region to deal with the security threats by 2020, he said. "The US will strengthen its presence in Asia-Pacific, and Japan will assume a larger role and responsibility in our alliance in the years ahead. A strong US militarily, economically and diplomatically is vitally important to this region and all who call it home," said Mr Pence.
Despite his declaration that the US has its sword ready, some analysts noted that the USS Ronald Reagan is in the middle of scheduled maintenance that will be completed only next month, with 100 pilots from its air wing yet to undergo training for deployment.
They also noted the confusion over the redeployment of the nuclear-powered aircraft carrier USS Carl Vinson, which had not been steaming towards the Korean peninsula as was initially implied.
Defence expert Tosh Minohara of Kobe University said: "America's sword is still in the scabbard and hasn't been drawn yet."
But he pointed to the build-up of US naval forces in the region. "This is much more than a pivot to Asia - the momentum is towards Asia. The entire centre of gravity has shifted to the region," he said.