President-elect Donald J. Trump has picked Pete Hegseth, a Fox News host and veteran of the wars in Iraq and Afghanistan, to lead the Pentagon and the 1.3 million active-duty men and women of the American military.

The choice of Mr. Hegseth, 44, was outside the norm of the traditional defense secretary. But he was a dedicated supporter of Mr. Trump during his first term.

“Pete is tough, smart and a true believer in America First,” Mr. Trump said in his announcement on Tuesday night. “With Pete at the helm, America’s enemies are on notice — our military will be great again, and America will never back down.”

But several Pentagon officials questioned Mr. Hegseth’s lack of experience — other than serving in the military — and raised concerns about his ability to win Senate confirmation, even with Republicans winning control of the chamber.

A Minnesota native, Mr. Hegseth graduated from Princeton University and has a master’s degree from Harvard. He has been married three times.

Here are other things to know about Mr. Hegseth.

He is a New York Times best-selling author.

Mr. Hegseth’s book, “The War on Warriors: Behind the Betrayal of the Men Who Keep Us Free,” was published in June.

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