U.S. Special Representative for North Korea Stephen Biegun said Wednesday the window was still open for Pyongyang to negotiate with the United States over its nuclear program, but it needed to seize the moment.

In remarks to the Senate Foreign Relations Committee in his nomination hearing for the State Department's No. 2 post, Biegun made a personal appeal to North Korea's First Vice Foreign Minister Choe Son Hui to engage in negotiations in a meaningful way.

Biegun 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.

Biegun has led U.S. efforts to try to persuade North Korea to denuclearize since last August, with little success so far.

He will retain his North Korean portfolio if, as expected, he is confirmed in his new position.

He said he expected his promotion would assist in the negotiation process, by further elevating the priority of the North Korea issues in which Choe would be his counterpart.

"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."

Biegun said U.S. President Donald 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.

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 U.S. ends what it called a policy of hostility.

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.

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 second summit between Trump and Kim 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.

North Korea has been demanding that sanctions hobbling its economy be lifted, and in April, Kim set a year-end deadline for Washington to show more flexibility. That raised concerns that North Korea could resume nuclear and long-range missile testing suspended since 2017 that Trump has repeatedly held up as a major achievement of his engagement with North Korea.