The United States and North Korea have made too much progress over the past year in their nuclear talks to return to where they were before negotiations started, a high-ranking official of the presidential office said Sunday.

His outlook comes amid growing uncertainty after North Korea threatened to quit nuclear talks with Washington following the breakdown of the summit between their leaders last month in Hanoi.

"North Korea and the US never want to go back to the days of conflict and confrontation seen before 2017," the Cheong Wa Dae official told reporters on condition of anonymity. "Both sides have moved forward too much to return to the past."

The official added that both sides have expressed an intention to keep talking to each other despite the collapse of the summit in Hanoi.

North Korean leader Kim Jong-un and US President Donald Trump met in the Vietnamese capital last month but failed to reach a deal as they were miles apart on how to match Pyongyang's denuclearization steps with sanctions relief from Washington.

In Pyongyang on Friday, North Korean Vice Foreign Minister Choe Son-hui said that North Korea is reconsidering whether to continue nuclear talks with the US and its moratorium on missile and nuclear tests.

She blamed Washington for the breakdown of last month's summit but did not make a direct criticism of Trump, saying Kim and Trump maintain good chemistry.

It is unclear whether Choe's remarks are aimed at putting pressure on Washington before resuming their nuclear negotiations or actually signal an end to the talks.

In response to Choe's remarks, US Secretary of State Mike Pompeo said that he is hopeful that nuclear negotiations with North Korea will continue. Earlier US Special Representative for North Korea Stephen Biegun said, "Diplomacy is still very much alive."

The Cheong Wa Dae official also said that it is necessary to reconsider the so-called "all-or-nothing" strategy in dealing with North Korea and called for both sides to reach an agreement on a roadmap first and then seek phased progress in denuclearization process.

This view appears to contradict Washington's push for a "big deal" in nuclear talks, while Pyongyang wants a phased and simultaneous approach in the denuclearization process.

He emphasized that Seoul and Washington are continuing close consultation to realize the ultimate goal of denuclearization of the Korean Peninsula and dismissed concerns that there might be differences in their North Korea approach. (Yonhap)