"We could just shoot some Patriot missiles and take out the labs, quietly," Trump suggested, according to the upcoming book "A Sacred Oath," the Times reported. The former President reasoned that Mexico didn't "have control" over its own country and that "no one would know it was us," Esper -- who objected at the time -- recounted, according to the Times.
The exchange is one of several stunning discussions detailed in Esper's book, which will be published on Tuesday, the newspaper reported. While Esper writes that Trump's behavior never became erratic enough to justify an invocation of the 25th Amendment, the book describes a chaotic White House focused almost entirely on Trump's reelection bid.
A spokesperson for Trump did not immediately respond to the Times' request for comment.
Esper broke with Trump at various times as defense secretary, including over the then-President's plans to withdraw all US troops from Afghanistan, but the rift deepened in summer 2020 when Esper said he did not support using active-duty troops to quell the large-scale protests across the United States triggered by the police killing of George Floyd.
Audio reveals GOP leader Kevin McCarthy planned to urge Trump to resign after Jan. 6 attack
Earlier this week, Axios reported that Esper's book also details Trump raising the idea of shooting protesters who took to the streets around the White House that summer.
"Can't you just shoot them? Just shoot them in the legs or something?" Trump asked, according to an excerpt in the book, Axios reported. CNN has previously reported similar accounts, including those documented by journalist Michael Bender in his own book titled "Frankly, We Did Win This Election: The Inside Story of How Trump Lost."
Trump ultimately fired Esper by tweet in early November 2020, days after losing the presidential election.
Esper told the Times on Thursday, "I felt like I was writing for history and for the American people," and called the former President "an unprincipled person who, given his self-interest, should not be in the position of public service."