President Trump has compared the CIA to Nazis. Now he is attacking the sentinels of American national security as “extremely … naive” on Iran, and much else. “They are wrong!” he tweeted on Wednesday. “Perhaps Intelligence should go back to school!”

The chiefs of U.S. intelligence, an enterprise costing well north of $80 billion a year, report that Iran isn’t building nuclear weapons, North Korea isn’t dismantling them, and the Islamic State is undefeated in Syria and Iraq. Trump batted back their conclusions on ISIS and North Korea in tweets delivered before dawn, in who knows what dark night of the soul.

“The President has a dangerous habit of undermining the intelligence community to fit his alternate reality,” tweeted Mark R. Warner (D-Va.), vice chairman of the Senate Intelligence Committee. “People risk their lives for the intelligence he just tosses aside on Twitter.”

The CIA’s spies and analysts are the lead reporters on these issues. All their work contradicts the president’s assumptions. And they are almost assuredly correct. Trump says they don’t know what they’re talking about. Why is he savaging American intelligence and its leaders? He may be playing deaf, dumb and blind to their work, fending it all off as fake news, because he thinks they have something on him. He certainly sees the CIA (and the FBI) as an instrument of a “deep state” conspiring to undo his presidency. And so he denigrates their work and dismisses their leaders as fools and naifs.

Sure, the CIA has been tragically wrong in the past. The United States went to war in Iraq 15 years ago, in part, because of its supposition that Saddam Hussein had weapons of mass destruction. But it’s just as great a tragedy when it gets it right and the president won’t listen. We are living through that kind of tragedy right now. If Trump trashes whatever the CIA tells him — just as he ignored its solid reporting that a certain Saudi prince had a contributing Washington Post journalist murdered four months ago — who knows what will happen if we have an actual crisis.

“It is sometimes difficult for us to understand the intensity of our public critics,” Richard Helms, the director of central intelligence from 1966 to 1973, once said. “Criticism of our efficiency is one thing, criticism of our responsibility quite another. ... If we are not believed, we have no purpose.”

Helms wasn’t terribly worried about the CIA’s critics in Congress or in the press back then; they were few. He was very much concerned with the critic-in-chief. The CIA, then and now, derives power by having the president’s ear.

Helms personally reported to the White House on Sept. 11, 1967, that North Vietnam had the will to win a war in which the United States was committing half a million troops. He wanted the president to know that “U.S. military power is ill-suited to cope with guerrilla warfare waged by a determined, resourceful, and politically astute opponent. This is not a novel discovery.” Lyndon B. Johnson didn’t want to hear that. He didn’t want to believe that Americans could lose the war in Vietnam. Nor did Richard Nixon, who wanted to win as much as LBJ did, and who savaged the CIA at every opportunity. “What the hell do those clowns do out there in Langley?” Nixon railed in 1970. Those presidents hated the CIA for challenging their assumptions and, thereby, undermining their aspirations.

This is different. The truth that everyone knew but no one would speak when America’s intelligence chiefs reported to the nation on Tuesday before the Senate Intelligence Committee is terrifying: the accumulating evidence that the president of the United States is a danger to our safety and security.

Their predecessors have been sounding the alarm for two and a half years.

In August 2016, Mike Morell, a 33-year CIA veteran and the agency’s deputy director and acting director under President Barack Obama, wrote in the New York Times that “Donald J. Trump is not only unqualified for the job, but he may well pose a threat to our national security.” Morell also endorsed Hillary Clinton for president, which surely did not endear him, and the CIA, to Trump. Retired Gen. Michael Hayden told the BBC a few days later that Trump would be “very dangerous indeed” if elected.

Last year, James R. Clapper Jr., director of national intelligence from 2010 to 2017, wrote: “I don’t believe our democracy can long function on lies. ... I believe we have to continue speaking truth to power, even — or especially — if the person in power doesn’t want to hear the truth we have to tell him.” And on Wednesday, John Brennan, CIA director from 2013 to 2017, had this to say to Trump in a tweet: “Your refusal to accept the unanimous assessment of U.S. Intelligence on Iran, No. Korea, ISIS, Russia, & so much more shows the extent of your intellectual bankruptcy. All Americans, especially members of Congress, need to understand the danger you pose to our national security.”

It’s a fact that Clapper and Brennan personally confronted Trump, two weeks before his inauguration, with what they believed was ironclad intelligence that Vladimir Putin had worked to elect him. It’s a fact that some of their colleagues suspect he may be an agent — unwitting or not — of a hostile power. And it’s a fact that the counterintelligence investigation of the president by special counsel Robert S. Mueller III relies in part on reporting by U.S. intelligence services.

Trump sees U.S. intelligence as a direct threat to his presidency — just as the most senior intelligence veterans see him as a danger to this country.

Thirty years ago, I interviewed William Colby, director of central intelligence from 1973 to 1976 and a lifelong CIA officer, in the first of many talks we had. He schooled me on an essential element of intelligence. It comes from the Jesuits. They tell us that there are two kinds of ignorance in this world. There is invincible ignorance — God is mysterious, we live in a fallen world, and some mysteries cannot be solved — and then there’s vincible ignorance. And that’s all the hard truths that you need to know, but you don’t want to know, because they are too hard to handle.

The kindest thing you can say about Trump and his contempt for U.S. intelligence is that he is vincibly ignorant. But there may be harsher truths that we have yet to learn.