The meeting between Pompeo and Kim Yong Chol, the former spy chief and now top nuclear negotiator, "will now take place at a later date. when our respective schedules permit", the US side said just after midnight on Wednesday, hours before Pompeo was supposed to travel to NY.
Pompeo said in an interview with CBS Sunday that he expects to make "some real progress" when he meets with his counterpart, including on the potential summit, "where we can make substantial steps towards denuclearization". "The United States remains focused on the fulfilment of the commitments made by the president Trump and president Kim at the summit in Singapore in June".
The State Department had said Monday that the two sides "will discuss making progress on all four pillars" of the Singapore summit, referring to a four-point joint statement signed by Kim Jong-un and Trump on June 12, and achieving the "final, fully verified denuclearization" of North Korea.
The diplomacy on North Korea has seen a series of fits and starts, with Trump at one point scrapping a trip by Pompeo just as he was set to fly to Pyongyang.
Presidential spokesman Kim Eui-kyeom said Seoul did not believe it would mean that the second summit would not take place and a senior South Korean foreign ministry official said that while the rescheduling was regrettable, there was no need to "overthink the postponement".
"We're very happy with how it's going with North Korea".
"I'd love to take the sanctions off, but they have to be responsive too - it's a two-way street", Trump said.More news: Tyson Chandler eager to ease LeBron James’ burden with Lakers
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North Korea's foreign ministry has warned that Pyongyang will "seriously" consider reviving its nuclear weapons program unless the sanctions are lifted. "We're in no rush", he said at a press conference.
Woo also pointed out that the Trump administration will face growing pressure to take issue with North Korea's human rights record, which could further complicate Washington's denuclearization talks with Pyongyang.
North Korea is also seeking a peace treaty with the United States and South Korea that will formally end the 1950-53 Korean War that split the communist North from the democratic South.
Diplomatic sources told CBS News reporter Kylie Atwood as recently as Monday that senior State Department officials were still confident in the plans for Pompeo's now-delayed meeting in NY.
Its leader, Kim Jong Un, has spoken of his hopes for reform of North Korea's economy and has looked to examples in the region.
South Korean President Moon Jae-in's spokesman Kim Eui-keum said the delay did not imply a collapse of the US nuclear negotiations with North Korea or a loss of momentum.