According to the Associated Press, the North accused the US of betraying the spirit of the summit between President Donald Trump and Kim Jong Un last month by making "one-sided and robber-like" for the "complete, verifiable and irreversible denuclearization of North Korea".
Despite the obstacles, Pompeo said on Saturday that progress had been made in the talks."These are complicated issues but we made progress on nearly all of the central issues", Mr. Pompeo said before departing on Saturday.
The spokeswoman, Heather Nauert, said Pompeo's discussions with North Korean officials included the repatriation of the remains of Americans who died in the Korean War in the 1950s in addition to denuclearization issues, according to a pool report by reporters accompanying Pompeo.
Kim, a regime hard-liner who is careful not to act outside North Korean leader Kim Jong Un's instructions, said he needed to "clarify" aspects of his almost three-hour negotiations Friday with Pompeo, a desire the top USA diplomat immediately echoed.
North Korea said Saturday that high-level talks with a USA delegation led by Secretary of State Mike Pompeo were "regrettable" and accused Washington of trying to unilaterally pressure the country into abandoning its nukes.
North Korea's state media said its "firm, steadfast" resolve to abadon its nukes may falter after the U.S. demanded unilateral denuclearisation during two days of talks in Pyongyang.
The North's statement, coming so soon after Pompeo's trip, was sure to fuel growing skepticism in the US over how serious Kim Jong Un is about giving up his nuclear arsenal.
"On this trip I'm seeking to fill in some details on these commitments and continue the momentum towards implementation of what the two leaders promised each other and the world", Pompeo said.
But Pompeo on Saturday did not directly answer some questions from reporters about how that process is going, after NBC News reported that North Korea is expanding some nuclear test sites.
Secretary of State Mike Pompeo has begun his first trip to Pyongyang since President Donald Trump's summit with leader Kim Jong Un last month with a vow to nail down the specifics of the commitments Kim made on denuclearization.
"The establishment of peaceful relations between the countries, increased security assurances to North Korea and its people, and finally, denuclearization", Pompeo said.
When a reporter asked about North Korea's Saturday comments, Pompeo didn't seem too bothered.
Both men said they needed to "clarify" certain elements of their previous discussions, but provided no detail.
As Saturday's meeting got under way Kim Yong-chol joked that Mr Pompeo may not have slept well during his overnight stay at a guesthouse in Pyongyang.
"The attitude and demands from the U.S. side during the high-level talks were nothing short of deeply regrettable", a spokesperson for the North Korean Foreign Ministry said in a statement. He added that the Trump administration was committed to reaching a deal under which North Korea would denuclearise and realise economic benefits in return. Amid speculation that Pompeo was forced to sideline the India meeting at Trump's insistence, many commentators have criticized what they see as a snub to New Delhi.
One hoped-for breakthrough on this trip would have been the return of the remains of US troops killed during the 1950-53 Korean War.
"We had anticipated the U.S. side would come with a constructive idea, thinking we would take something in return", the North Korean statement said, warning its "resolve for denuclearisation. may falter".