WATCH Former UN Amb. on revived NK summit: ‘Danger now is this will be a gigantic photo op’

A former adviser to President Donald Trump said North Korean leader Kim Jong Un hasn’t yet met the U.S. leader and he “better prepare for” that.

Tom Bossert, an ABC News contributor and former White House adviser on homeland security and counterterrorism, told ABC News Chief Anchor George Stephanopoulos on “This Week” Sunday, that he has some advice for Kim ahead of the planned summit between him and President Trump.

“Just a thought here, we’ve all given advice to President Trump. I think a little advice to Kim Jong Un” is in order, Bossert said. “First, he’s not met President Trump yet and he better prepare for that.”

Kim has met with a member of Trump’s inner circle — Mike Pompeo, who is now secretary of state and was formerly CIA director. But the planned June 12 summit would be the first time Kim and Trump meet.

Bossert’s second piece of advice to Kim was about North Korea‘s recent, highly publicized destruction of a site where it had tested nuclear weapons.

“These demonstrations of blowing up tunnels, whether they’re complete or whether they’re facades, just for show, it’s really not helping matters,” Bossert said. “Even if they believe that to be a helpful gesture, it does make later confirmation of our [nuclear] inspectors, and what was in those tunnels all that more difficult. And so to build trust, I think that they should stop taking those unilateral actions at this point.”

North Korean envoy Kim Yong Chol shakes hands with President Donald Trump as Secretary of State Mike Pompeo looks on after a meeting at the White House, June 1, 2018 in Washington, D.C.

Bossert appeared on “This Week” as part of a panel discussing…