PALM BEACH, Fla. (Reuters) - U.S. President Donald Trump on Tuesday brushed off North Korea’s warning of a “Christmas gift,” saying the United States would “deal with it very successfully,” amid U.S. 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 United States to work out “a feasible roadmap for establishing a permanent peace regime & realizing complete denuclearization on the (Korean) Peninsula.”

North Korea warned this month of a possible “Christmas gift” for Washington after Kim gave the United States 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,” Trump told reporters at his Mar-a-Lago resort. “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 denuclearization talks ahead of Trump’s re-election bid next year and said it was “entirely up to the U.S. what Christmas gift it will select to get.”

U.S. 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.

Trump has repeatedly held up the test suspensions as evidence that his policy of engaging with North Korea works.

ICBM TEST IN 2017

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.

Trump and 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 United States 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 denuclearization of the Korean peninsula.”

U.S. President Donald Trump speaks to the media after participating in a video teleconference with members of the U.S. military at Trump's Mar-a-Lago resort in Palm Beach, Florida, U.S., December 24, 2019. REUTERS/Leah Millis

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.

China and Russia, proposed last week that the U.N. Security Council lift some sanctions to break the current deadlock.

A U.S. 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 denuclearization, 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 U.S. officials have said Kim promised Trump he would close.

Pyongyang said the tests were aimed at “restraining and overpowering the nuclear threat of the U.S.”