US Ambassador to the UN, Kelly Craft, chairs a UN Security Council meeting on "Non-proliferation/Democratic People's Republic of Korea," December 11, 2019, at UN Headquarters in New York. - The US warned North Korea of consequences if it makes good on threats of a spectacular missile test in the New Year, while offering flexibility if it stays in talks. "We trust that (North Korea) will turn away from further hostility and threats, and instead make a bold decision to engage with us," Craft said at the meeting. (Photo by Eskinder DEBEBE / UNITED NATIONS / AFP)

The United States is ready to be flexible in negotiations with North Korea on dismantling the regime's nuclear weapons program, the U.S. envoy to the United Nations said Wednesday, urging Pyongyang to refrain from provocations.

Ambassador Kelly Craft made the remarks at a U.N. Security Council session as Pyongyang's year-end deadline for nuclear negotiations with Washington draws near.

Amid indications the North is preparing to launch a long-range missile, Craft warned that such activity will only complicate efforts to implement an agreement reached by U.S. President Donald Trump and North Korean leader Kim Jong-un at their first summit in Singapore in June 2018.

"We remain ready to take actions in parallel, and to simultaneously take concrete steps toward this agreement," Craft told the Council in New York, in live online footage.

"We are prepared to be flexible ... and we recognize the need for a balanced agreement that addresses the concerns of all the parties," she continued. "But we cannot do this alone. North Korea must make this difficult but bold decision to work with us."

Speaking to reporters before the meeting, she said North Korea "must do its part, and it must avoid provocations."

Trump and Kim agreed in Singapore to "work toward" complete denuclearization of the Korean Peninsula in exchange for U.S. guarantees and also pledged to improve the two countries' acrimonious relations.

But progress has been slow amid persisting gaps over how much North Korea will need to denuclearize in order to receive sanctions relief and other concessions from the U.S.

North Korea has strongly suggested it will return to testing nuclear bombs and intercontinental ballistic missiles if the U.S. fails to offer concessions in their stalled negotiations by the end of the year.

Reinforcing the concerns, North Korea on Saturday conducted what it called a "very important test" at its western satellite launch site. South Korea has said it involved a rocket engine.

"We hope that we do not find ourselves at an inflection point in the near future," Craft said. "We trust (North Korea) will turn away from further hostility and threats, and instead, make a bold decision to engage with all of us."