The book by CNN's Jim Sciutto also contains quotes about the former president's reported "admiration" of Hitler.

John R. Bolton served as national security adviser to President Donald Trump and as U.S. ambassador to the United Nations under President George W. Bush. He is the author of The Room Where It ...

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.

NPR's Scott Simon talks to former National Security Adviser John Bolton about the foreign policy implications of Friday's shocking press conference between President Trump and President Zelenskyy.