John Bolton suggests Trump's North Korea strategy will never work

• He did say, though, that he has a "self-imposed restriction" on discussing specifics from his time in the White House.

Bolton told an audience at the Center for Strategic and International Studies that North Korea was and would continue to be committed to keeping and expanding its nuclear weapons program, rendering Trump’s summit-based strategy pointless.

• He contended North Korea wouldn’t "ever voluntarily give up enough" in negotiations, and said the U.S. should consider a military option. He cited regime change as one potential outcome.
• He also raised the "Libya model" of denuclearization — a comparison that outraged North Korea and, as a result, Trump when he referenced it while serving in the White House. Libyan dictator Moammar Gadhafi was toppled a decade after giving up his nuclear program.

On his personal impressions of Kim Jong-un, Bolton said: "I think it's clear he’s in charge. I think it's clear he makes the decisions. And I think he feels very comfortable in that role."

• Bolton said he was sure "the leadership of North Korea is delighted I'm here today in a private capacity," rather than in the White House.

The big picture: Bolton argued that the U.S. should be more deeply engaged around the world and must strengthen ties with allies — views that runs contrary to Trump's.

Go deeper: Bolton's chaotic White House departure