Talking to reporters at the Foggy Bottom headquarters of the US State Department, he said Donald Trump and the world have set the "conditions" for a successful outcome from the June 12 summit between the US President and Kim in Singapore.
But White House aides have been eying Singapore, a tiny island nation of 5.6 million that boasts one of the most advanced economies in Southeast Asia. "We're now waiting for a response from Pyongyang".
As they got off the plane, they were in great spirits though clearly exhausted.
The country has been the site of other high-profile summits. The U.S. has nearly 30,000 soldiers stationed in the country.
Since Mr Trump announced plans to hold a summit with Mr Kim, questions have been raised continually about whether the two leaders have the same objective in mind when they speak about "denuclearisation".
Britons kidnapped in ambush at Congolese national park
Virunga is home to about one-quarter of the world's remaining mountain gorillas , and the work of protecting them has proven risky .
The head of the UN's World Food Programme (WFP) believes there is a "sense of optimism" among North Korea's leaders after enjoying what he said was unprecedented access to the country.
"His parents have become friends, spectacular people - they are really incredible people", he said.
The perception among North Koreans that their nation's nuclear strength has finally forced a sitting USA president to the negotiating table contrasts sharply with Trump's narrative.
But Singapore also has rigorously sought to maintain good relationships with US rivals, especially China, which has flexed its economic and military muscle as Beijing seeks to expand influence in Southeast Asia.
Ironically enough, the two countries don't even agree on that history.
Following the Moon-Kim summit, Moon's office said Kim was willing to disclose the process to worldwide experts, but the North's statement Saturday didn't include any mention about allowing experts on the site.
President Moon Jae-in vowed to expand cross-border exchanges with North Korea on Friday, saying an increase in exchanges may eventually lead to the unification of the divided Koreas. It's the result of strong diplomatic efforts by this administration, particularly Secretary Pompeo, but there is still a long way to go to address the grotesque human rights abuses still happening in North Korea.
"Some great things can happen, and that's what we hope", he added. Trump has said any deal will have to include the denuclearization of the rogue nation.