President Donald Trump has brushed off North Korea's warning of a "Christmas gift", saying the United States would "deal with it very successfully", amid concerns that Pyongyang might be preparing a long-range missile test.
China, North Korea's most important backer, meanwhile urged Washington to take "concrete steps" as soon as possible to implement agreements reached during last year's summit between Trump and North Korea leader Kim Jong-un in Singapore.
Chinese Foreign Minister Wang Yi, in comments relayed on Twitter by the foreign ministry in Beijing, called on North Korea and the US to work out "a feasible roadmap for establishing a permanent peace regime & realising complete denuclearisation on the (Korean) Peninsula."
North Korea warned this month of a possible "Christmas gift" for Washington after Mr Kim gave the US until the end of the year to propose new concessions in talks over his country's nuclear arsenal and reducing tensions between the adversaries.
"We'll find out what the surprise is and we'll deal with it very successfully," Mr Trump told reporters at his Mar-a-Lago resort on Tuesday. "We'll see what happens."
"Maybe it's a nice present," he quipped. "Maybe it's a present where he sends me a beautiful vase as opposed to a missile test."
In issuing its warning, North Korea accused Washington of trying to drag out denuclearisation talks ahead of Mr Trump's re-election bid next year and said it was "entirely up to the US what Christmas gift it will select to get".
US military commanders have said that the North Korean response could involve the testing of a long-range missile, something North Korea has suspended, along with nuclear bomb tests, since 2017.
Mr Trump has repeatedly held up the test suspensions as evidence that his policy of engaging with North Korea works.
North Korea's last test of an intercontinental ballistic missile was in November 2017 when it fired a Hwasong-15, the largest missile it has ever tested.
Pyongyang said the missile was capable of reaching all of the United States.
Mr Trump and Mr Kim have met three times since 2018, but there has been no substantive progress. North Korea has demanded an end to international sanctions while the US says Pyongyang must first commit to giving up its nuclear weapons.
At their unprecedented first summit in Singapore in 2018, the two sides agreed to work together to build a "lasting and stable peace regime" to replace the 1950-53 Korean War armistice, while North Korea committed "to work toward complete denuclearisation of the Korean peninsula".
Recent days have seen a flurry of international diplomacy aimed at avoiding a return to the heated confrontation seen two years ago that raised fears of war.
North Korean Supreme Leader Kim Jong Un rides a white horse near Mount Paektu. Source: KCNA - Korean Central News Agency
China and Russia, proposed last week that the UN Security Council lift some sanctions to break the current deadlock.
A US State Department official responded by saying it was not the time to consider doing this when North Korea was "threatening to conduct an escalated provocation, refusing to meet to discuss denuclearisation and continuing to maintain and advance its prohibited weapons of mass destruction and ballistic missile programs".
North Korea has conducted repeated tests of short-range missiles this year and this month carried out what appeared to be engine tests at a rocket-testing facility US officials have said Mr Kim promised Mr Trump he would close.
Pyongyang said the tests were aimed at "restraining and overpowering the nuclear threat of the US".
