WASHINGTON (Reuters) - U.S. Special Representative for North Korea Stephen Biegun said on Wednesday a year-end deadline North Korea has set for Washington to show more flexibility in nuclear talks was an artificial one, but could mean a return to “provocative” steps that preceded the past two years of diplomacy.

FILE PHOTO: U.S. special envoy for North Korea Stephen Biegun pictured here attending as U.S. President Donald Trump meets with Korea’s President Moon Jae-in in New York, U.S. September 23, 2019. REUTERS/Jonathan Ernst/File Photo

North Korea has been demanding the lifting of sanctions hobbling its economy and its leader Kim Jong Un set the deadline for Washington to show more flexibility in April, raising concerns he could resume nuclear and long-range missile testing suspended since 2017.

U.S. President Donald Trump has repeatedly held up this suspension as a major achievement of his engagement with North Korea, but in his nomination hearing for the State Department’s No. 2 post, Biegun suggested this could come to an end.

“I can imagine that we could see a possibility of going back to some of the more provocative steps that preceded the start of this diplomacy to begin with,” Biegun told the Senate Foreign Relations Committee.

“I think that would be a huge mistake and a missed opportunity by the Democratic People’s Republic of Korea,” he said.

Biegun said the United States would stick to its efforts to resolve the North Korea issue “for as long as it takes.”

“We do not have a year-end deadline ... That’s an artificial deadline set by the North Koreans, and unfortunately it’s a deadline that they’ve set upon themselves.”

Biegun’s remarks came after repeated statements from North Korea in recent days that it has no interest in talks with the United States unless the Washington ends what it called a policy of hostility.

Biegun, who has led U.S. efforts to try to persuade North Korea to denuclearize since last August, told the committee there had been no concrete evidence that North Korea had made a decision to give up its nuclear weapons, but he still believed Pyongyang could make this choice.

‘WINDOW STILL OPEN’

Biegun will retain his North Korean portfolio if, as expected, he is confirmed in his new position. He said he believed his promotion would assist in the negotiation process, by further elevating the priority of the North Korea issues.

“The person who needs to negotiate with me in North Korea is the First Vice Minister of Foreign Affairs Choe Son Hui. So far, she has not participated in these negotiations in a meaningful way,” he said.

“The window is still open but the North Koreans should not miss this opportunity,” Biegun added. “They need to seize the moment.”

Earlier on Wednesday, South Korea’s Yonhap news agency quoted Choe as saying that discussions related to the nuclear issue might have been taken off the negotiating table given the U.S. attitude.

“I think the nuclear issue can be discussed again when the U.S. abolishes all hostile policies toward North Korea,” it quoted her as saying during a visit to Moscow.

Biegun said Trump had created the opportunity for a solution to the North Korean issue and the desire for this was shared by leaders in South Korea, Japan and even China and Russia.

“The president remains of the view that Chairman Kim Jong Un can make this decision to move forward, and if so, the world and certainly the Korean Peninsula, will be a much more peaceful place,” he said.

Joel Wit, a former State Department diplomat who now runs 38 North, a Washington-based North Korea research project, said prospects for diplomacy did not look good.

“We are not in a good spot,” he told a seminar at Washington’s United States Institute of Peace think tank. “I would say that the chances are 80-20 that by the end of the year the diplomacy is going to fail.”

He said North Korea could be trying to squeeze more concessions out of the United States, but he added:

“We need to be prepared for failure ... I don’t know how the North Koreans will proceed, but there certainly may be missile tests at the very least. Nuclear tests, I don’t know.”

Trump and North Korea’s Kim have met three times since last year to push forward negotiations Washington hopes will lead to North Korea dismantling its nuclear and missile programs.

The talks have made no significant progress and a Trump-Kim summit collapsed in Vietnam in February.

The two leaders agreed in June, at a third meeting, to reopen negotiations, but working-level talks in October in Sweden, led by Biegun on the U.S. side, ended with the North Korean envoy accusing the Americans of coming to the table empty-handed.