Jonathan Karl's new book details how John Kelly shot down Trump's war plan for Venezuela

ABC's Jonathan Karl writes in "Front Row at the Trump Show," out Tuesday, that during a meeting in 2017, President Trump interrupted a presentation by then-national security adviser H.R. McMaster on the deteriorating situation in Venezuela, and demanded a war plan. "I will pass that order on to the Pentagon immediately, Mr. President," McMaster replied.

The big picture: Karl writes that one of the options Trump "had in mind was a naval blockade of Venezuela, which didn't make sense for a lot of reasons, including the fact that Venezuela is not an island."

As McMaster marched into his office, then-chief of staff John Kelly hustled after him, Karl writes:

"What the hell are you doing?" Kelly asked.

"I am going to carry out an order from the commander in chief," McMaster answered.

Kelly told him to stand down and not to pass the president's order on to the Pentagon.

Why it matters: It's a juicy example of the approach Kelly, who tried to bring discipline to a chaotic West Wing, took to corralling Trump.

• At a crowded sports bar in Manila during a presidential trip, Kelly told Karl that "the most important thing he did was tell the president no. 'No. Don’t tweet that. No. Don’t change your policy on that. No, no, no.'"

Between the lines: When Karl went to Kelly and asked if he could use a certain off-the-record exchange in the book, the retired general had a surprisingly blanket response, Karl writes in a footnote: "[H]e agreed to allow me to quote this and other previously off-the-record remarks he made while he was chief of staff."

Go deeper ... New book: Steve Bannon called Nancy Pelosi "an assassin"