President Trump’s top aides were so worried about his plans to scrap two major trade deals that they swiped the orders off his desk — and he didn’t even notice, according to a new book on the White House.

The Washington Post on Tuesday published a report on the explosive book, “Fear: Trump in the White House,” by famed Watergate journalist Bob Woodward.

In one example, Woodward wrote that then-economic adviser Gary Cohn “stole a letter off Trump’s desk” that the president planned to sign pulling the United States from a trade agreement with key ally South Korea.

Cohn later told a colleague that he removed the letter to protect national security and that Trump didn’t even notice that it went missing.

Cohn repeated his chicanery to stop Trump from withdrawing from the North American Free Trade Agreement, which he had vilified on the campaign trail.

In spring 2017, Trump harangued then-White House secretary Rob Porter over the issue.

“Why aren’t we getting this done? Do your job. I want to do this,” the commander in chief said.

Porter dutifully drafted a letter withdrawing from NAFTA, but he and other advisers feared it could trigger an economic and foreign-relations disaster, so Porter consulted Cohn.

“I can stop this,” Cohn replied. “I’ll just take the paper off his desk.”

In another move to short-circuit Trump, Defense Secretary James Mattis allegedly ignored an order to kill Syrian dictator Bashar al-Assad after Assad launched a chemical-weapons attack on civilians in April 2017.

“Let’s f–king kill him! Let’s go in. Let’s kill the ­f–king lot of them,” Trump said, according to Woodward.

Mattis told Trump he’d get right on it, but then told a senior aide, “We’re not going to do any of that. We’re going to be much more measured.”

The president’s national security team, with Trump’s approval, instead launched an airstrike on the Syrian base that launched the attack.

Trump also flunked a practice grilling to prepare for a sit-down with special counsel Robert Mueller, stumbling while answering questions, telling falsehoods and contradicting himself before exploding in anger, according to the book.

Trump’s lawyer at the time, John Dowd, was convinced that the president would commit perjury if he talked to Mueller, so he arranged for a practice session on Jan. 27.

“This thing’s a goddamn hoax,” Trump raged, beginning a 30-minute rant that concluded with him saying, “I don’t really want to testify,” the paper reported.

Weeks later, on March 5, Dowd and Trump lawyer Jay Sekulow met with Mueller and his deputy, telling the prosecutors about the president’s disastrous practice session and why they thought Trump should skip the sit-down.

“I’m not going to sit there and let him look like an idiot,” Dowd said, according to the book. “And you publish that transcript, because everything leaks in Washington, and the [leaders] overseas are going to say, ‘I told you he was an idiot. I told you he was a goddamn dumbbell. What are we dealing with this idiot for?’ ”

Mueller replied, “John, I understand,” according to Woodward.

Days later, Dowd told Trump: “Don’t testify. It’s either that or an orange jumpsuit.”

Dowd denied the remark, The Washington Examiner reported.

Woodward tried to interview Trump, but a meeting was never arranged because the request was rejected by Chief of Staff John Kelly, who was still smarting over previous tell-alls by Omarosa Manigault Newman and Michael Wolf.

Woodward also wrote that Trump’s national security team was stunned by the president’s ignorance of world affairs and his contempt for the views of military and intelligence leaders.

At a National Security Council meeting on Jan. 19, Trump seemed disinterested in the massive US military presence on the Korean Peninsula, including an intelligence operation that allowed the US to detect a North Korean missile launch in seven seconds rather than the 15-minute warning the military could provide from Alaska. Trump questioned why the US was spending so much in the region.

“We’re doing this in order to prevent World War III,” Mattis allegedly told him.

After Trump left, “Mattis was particularly exasperated and alarmed, telling close associates that the president was like ‘a fifth- or sixth-grader,’ ” Woodward wrote.

Kelly frequently lost patience with the president and told colleagues he thought Trump was “unhinged,” according to Woodward.

In one meeting, Kelly allegedly said: “He’s an idiot. It’s pointless to try to convince him of anything. He’s gone off the rails. We’re in Crazytown. I don’t even know why any of us are here.”

Trump also called Attorney General Jeff Sessions — the first senator to back him — a “traitor” during one meeting, according to the book.

“This guy is mentally retarded. He’s this dumb Southerner,” Trump said, affecting an exaggerated Southern accent. “He couldn’t even be a one-person country lawyer down in Alabama.”

The book also revealed a rare admission from Trump that he had made a mistake after the white-nationalist riot last summer in Charlottesville, Va. — by walking back his earlier remarks that “both sides” were to blame for violence at the raucous event.

“That was the biggest f–king mistake I’ve made” and the “worst speech I’ve ever given,” he said, according to Woodward’s account.

Trump dismissed the book in an interview Tuesday with The Daily Caller.

“It’s just another bad book. He’s had a lot of credibility problems,” Trump said of Woodward.

Trump specifically denied Cohn took papers from his desk, saying “there was nobody taking anything from me” and suggesting that, “It could be just made up by the author.”

Administration spokeswoman Sarah Huckabee Sanders also slammed the book in a statement in which Kelly denied ever calling the president an idiot.