Secretary of Defense Jim Mattis reportedly lashed out at Sean Spicer after the former White House press secretary repeatedly tried to get him to go on Sunday morning talk shows, according to a soon-to-be-released book by journalist Bob Woodward.

Spicer apparently tried numerous times to get the secretary of defense to go on television, finally causing an exasperated Mattis to respond with a statement far clearer than a simple “no.”

“Sean,” Mattis said, according to an excerpt of the book, “Fear,” obtained by CNN. “I've killed people for a living. If you call me again, I'm going to f*cking send you to Afghanistan. Are we clear?”

The secretary of defense has made only one televised appearance on a network show since the start of the Trump presidency. He appeared on CBS' “Face the Nation” in May 2017, when he told host John Dickerson that nothing keeps him awake at night, adding, “I keep other people awake at night.”

Just prior to the most recent Pentagon briefing, Mattis revealed to reporters that he takes no pleasure in standing up in front of the cameras and addressing a large audience.

Woodward's book, the topic of much discussion this week, also claimed that Mattis privately criticized President Donald Trump for having the understanding of “a fifth- or sixth-grader” after a particularly trying meeting, The Washington Post reported Tuesday.

Related: 6 Alarming Passages From Bob Woodward’s Account Of Mattis Vs. Trump »

Mattis also reportedly had to rein in U.S. policy after a phone call in which the president supposedly ranted about wanting to “f*cking kill” Syrian President Bashar al-Assad.

In response to Woodward's reporting, Mattis issued a statement Tuesday condemning the book as a “uniquely Washington brand” of “fiction.”

“The contemptuous words about the President attributed to me in Woodward's book were never uttered by me or in my presence,” Mattis explained, “While I generally enjoy reading fiction, this is a uniquely Washington brand of literature, and his anonymous sources do not lend credibility.”

“In serving in this administration, the idea that I would show contempt for the elected Commander-in-Chief, President Trump, or tolerate disrespect to the office of the President from within our Department of Defense, is a product of someone's rich imagination,” he added.

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