ZELENSKYY: You think... TRUMP: You're gambling with World War III. SIMON: John Bolton joins us now. Mr. Bolton was ambassador to the United Nations during the George W. Bush administration.

Of course, yesterday, President Trump met with Ukraine's President Volodymyr Zelenskyy just after the third anniversary of the Russian invasion of his country and told him... (SOUNDBITE OF ARCHIVED ...

What advice would John Bolton give to Sir Keir Starmer? One official from the Donald Trump's first term who refused to toe the line was his former national security adviser John Bolton.