In his final days in the White House, President Donald Trump tried to launch a U.S. military withdrawal from Afghanistan -- only he wasn't exactly the person giving the orders, according to a new book by ABC News Chief Washington Correspondent Jonathan Karl.

In "Tired of Winning: Donald Trump and the End of the Grand Old Party," excerpts of which were released in Vanity Fair on Friday, Karl reports that aide Johnny McEntee, known as Trump's "body guy," led a chaotic attempt to reshape the U.S. military posture abroad.

The incident was first reported on by Jonathan Swan of Axios, but Karl provides significant new details.

McEntee, after serving as Trump's "body guy" (or "body man" as some say) -- the staffer responsible for traveling with the president and carrying his bags -- became, at age 30, the director of the Presidential Personnel Office, primarily responsible for overseeing the hiring and firing of executive branch employees, including ensuring staffers were loyal to Trump's political vision.

But after the 2020 election, Karl writes, McEntee took on a greater role -- one that saw him involved in Trump's ousting of Defense Secretary Mark Esper -- replacing him with Christopher Miller -- and the recruiting of Miller's senior adviser Douglas Macgregor.

From there, Karl reports, McEntee wrote a list for what Trump should do in the final days of his presidency -- a list that included withdrawing U.S. forces from Afghanistan, Iraq, Syria and Africa.

"Three days after Macgregor arrived at the Pentagon, he called McEntee and told him he couldn't accomplish any of the items on their handwritten to-do list without a signed order from the president," Karl writes in the excerpts released by Vanity Fair.