Secretary of State Mike Pompeo is in North Korea, where he could meet with Kim Jong Un. He landed in Pyongyang Friday for the first time since President Trump met Kim at a summit in Singapore last month. Pompeo said he's looking to "fill in some details" on North Korea's offer to denuclearize.

Pompeo's visit "will be a real test" of whether Kim is serious about denuclearization or not, according to CBS News senior national security contributor Michael Morell, former deputy and acting director of the CIA. Morell said three things need to happen during Pompeo's stay.

"One is North Korea has to make a declaration of its nuclear capabilities. Numbers of weapons, where they are, how much fissile material they have, where those production facilities are, who they are, where the scientists are, how many there are – a complete and truthful declaration," Morell said Friday on "CBS This Morning." "Then there has to be a negotiation for how they dismantle all of that and what we give in return, right, and at what timetable both of those things happen. And then the last piece is how do you verify going forward that they live up to their agreement and don't start cheating?"

Morell said he hopes Pompeo will come back with a specific timetable for the declaration.

"When are they going to hand us that piece of paper? I would hope it's two or three months from now," Morell said.

The meeting comes as North Korea is reportedly expanding a missile-manufacturing site. Morell said Pompeo is testing whether Kim is lying about his commitment "to work toward complete denuclearization."

"We have a pretty good understanding of what [Kim] has, including some things that he's never acknowledged to the international community before," Morell said.

As for reported government leaks about North Korea's intention to denuclearize, Morell said, "I would imagine that there is some concern among officials, particularly on the policy side, that the president will only negotiate on what Kim and the North Koreans have before acknowledged to the International Atomic Energy Agency, right, acknowledged to the international community. What these leaks I think are trying to do is say there's a bigger program here. Make sure you cover it all. And trying to box the president in a little bit."