At the same time the USA state department was forced to deny reports Mr Pompeo gave Kim Jong Un a CD of Elton John's Rocket Man - a playful reference to Donald Trump's nickname for the North Korean leader.
U.S. Secretary of State Mike Pompeo, Japan's Foreign Minister Taro Kono and South Korea's Foreign Minister Kang Kyung Wha speak with each other after a news conference in Tokyo, Japan, July 8, 2018.
"Clearly, we see some posturing particularly from the North Korean side using the leverage that they have, especially in the lead-up to Trump's visit to NATO and his big summit with [Russian President] Vladimir Putin in the coming week", said Hilary Mann Leverett, a former White House official.
Pompeo said he had also pushed North Korea on a promise to destroy a missile engine test site and that the United States would like that to happen "soon".
Nauert's confirmation comes after Pompeo was rather coy about the alleged gift when reporters asked him about it upon arriving to North Korea on Friday.
In the statement calling the United States stance "regrettable", the North Korean Foreign Ministry spokesman quoted by KCNA said the USA is unilaterally demanding denuclearisation and trying to postpone discussion of declaring an end to the Korean War.
North Korea apparently didn't get the memo.
Pompeo left North Korea without meeting directly with leader Kim Jong Un, as he has during previous visits.
Pruitt is gone. But that doesn’t mean the environment is safer
James Inhofe (R-OK), including as chief counsel for the senator on the Senate Environment and Public Works committee. Widespread disgust for Pruitt "should serve as a blaring red siren for the Trump administration", Udall said.
It says pressure will remain until North Korea denuclearizes, but in statements this week, it redefined the USA goal as "the final, fully verified denuclearization" of the country.
Earlier, Pompeo and Kim Yong-chol both said they needed clarity on the parameters of an agreement to denuclearise the Korean peninsula that Trump and the North Korean leader had agreed to in Singapore.
At that meeting, Trump lavished praise on Kim and agreed to suspend America's joint military exercises with South Korea in the region.
The outcome of the latest US-North Korean talks on denuclearization was clearly a matter of perspective.
He had said progress was made during his two-day visit to Pyongyang.
"Sanctions will remain in place until final, fully verified denuclearisation as agreed to by Chairman Kim (Jong Un) occurs", Pompeo said, adding that the U.S. would seek to smooth the path by providing security guarantees requested by Pyongyang.
Officials from the two sides would meet next week in Panmunjom, on the border between the two Koreas, to discuss the return of the remains of the some 7,000 US soldiers still listed as missing in action since the 1950-53 Korean War.
The task of establishing the disarmament program now falls to Pompeo, who is seeking a formal declaration by the North of the size of its nuclear program, as well as an eventual timetable for it to be ended under global verification and inspection.
Last month, Trump told a crowd of supporters that the remains of 200 service members had "been sent back", but US military officials later said that was not the case.
The day began with Mr Pompeo and Kim Yong-chol both saying there were things to "clarify". Some places, a great deal of progress.