'Not aware' of any contact between US and North Korea since Hanoi summit, but President Donald Trump ‘prepared to engage again’: White House national security adviser John Bolton Bolton said Trump is "open to a third summit," but nothing's been scheduled yet.

In the wake of recent satellite images showing new activity at the Sohae (Tongchang-ri) launch facility in the northwestern part of North Korea, President Donald Trump's national security adviser said he's "not aware" of any contacts between the U.S. and North Korea since the summit in Hanoi, Vietnam.

The images, which were published by the Center for Strategic International Studies’ (CSIS) Beyond Parallel, appear to show a rapid rebuilding at the country’s main site for long-range satellite launches and missile-engine testing.

John Bolton told "This Week" co-anchor Martha Raddatz on Sunday that it’s possible the South Korean government has spoken to North Korea about the activity. He added that he will be speaking with his South Korean counterpart Monday morning and he suspects the satellite images will be discussed.

"I'd rather not get into the specifics" on the images," Bolton said. "The United States government -- I'll just put it this way -- spends a lot of resources and efforts so we don't have to rely on commercial satellite imagery. We've seen a lot in North Korea. We watch it constantly. ... There's a lot of activity all the time in North Korea, but I'm not going to speculate on what that particular commercial satellite picture shows."

"What can you tell us?" Raddatz pressed. "You’ve been doing this for years. Give us some idea whether that concerns you."

"The president has been very clear that he's not going to make the mistakes of prior administrations. And one mistake that prior administrations made repeatedly was assuming that the North Koreans would automatically comply when they undertake obligations," Bolton said. "The North Koreans for example, have pledged to give up their nuclear weapons program at least five separate times, beginning in 1992 with the joint North/South denuclearization agreement.

"They never seem to get around to it though. So that's one reason why we pay particular attention to what North Korea is doing all the time. We see exactly what they’re doing now. We see it unblinkingly, and we don't have any illusions about what their capabilities are."

The facility in the satellite images had been inactive since August, following Trump’s Singapore summit with Kim earlier that summer. During the summit, Kim committed to dismantling a launch facility.

The renewed activity at the launch site was detected just two days after the second Trump-Kim summit in Vietnam, which failed to reach an agreement to eliminate North Korea's nuclear weapons program. However, Trump told reporters that like the Singapore summit, Kim had committed to not conducting nuclear or ballistic missile tests.

Asked about the images on Wednesday, Trump said "it’s too early to see" if North Korea is breaking a promise by rebuilding the site.

"I would be very disappointed if that were happening. It’s a very early report," Trump said. "But I would be very, very disappointed in Chairman Kim. And I don’t think I will be, but we’ll see what happens. We’ll take a look. It’ll ultimately get solved."

On Saturday, CSIS’s Beyond Parallel published more satellite images taken on Wednesday and Friday that appear to show work has continued at the site.

"What would the consequences be if we saw another test launch?" Raddatz asked Bolton Sunday on "This Week."

"As the president said, he’d be pretty disappointed if Kim Jong Un went ahead and did something like that. The president said repeatedly that he feels the absence of nuclear tests, the absence of ballistic missile launches is a positive sign," Bolton said. "He’s used that really as part of his effort to persuade Kim Jong Un that he has to go for what the president called the big deal, complete denuclearization."

Bolton said that it would be a mistake to fall "for the North Korean action for action ploy" because it doesn’t work.

"What North Korea needs -- and it needs it very much right now -- is economic relief. ... [Kim] wants the economic sanctions released. And to get that, he is prepared to give up some part of his nuclear program, perhaps at a declaratory level, even a substantial part," Bolton said.

"But the marginal benefit to North Korea of economic relief is far greater than the marginal benefit to us of partial denuclearization. So that's why, action for action, almost inevitably in the past three administration has worked to North Korea's benefit."

Bolton said the sanctions put pressure on North Korea, which is to the United States’ advantage.

"It's one reason why all of the pundits and all of the experts predicting a deal in Hanoi were wrong, because the leverage is on our side right now, not on North Korea's," he said.