Former White House counterterrorism czar Richard A. Clarke, who worked directly under three presidents during his 30 years in government, still believes his ex-boss George W. Bush was the worst of them all.

Yet Clarke—whose new book, The Fifth Domain, chronicles the dire threats to the United States posed by cyberwarfare—says Donald Trump is very likely, in the end, to wreak even more havoc.

“He’s eviscerating the government. He’s eviscerating capabilities that we need,” Clarke told The Daily Beast this week as the Los Angeles Times reported that the Trump administration had “gutted programs aimed at detecting weapons of mass destruction”—rigorous local and national training programs that Clarke had a hand in starting. “And it’s not as though if the Democrats win the 2020 election you just turn those capabilities back on. The people go away, the skill sets go away, the capabilities atrophy. And it will take years to undo the damage.”

Clarke added: “You’ve got to wonder if the cumulative effect of a million bad decisions equates to the disasters caused by one big bad decision that Bush made”—namely, the ruinous military adventure in Iraq that Bush 43 sold to Congress and the American people as a justifiable response to the terrorist attacks of Sept. 11, 2001, which Iraqi tyrant Saddam Hussein had nothing to do with. “But we’re getting there,” Clarke added, referring to Trump.

But couldn’t Trump just end up blundering through his presidency without inviting a catastrophe?

“I think the chances of that,” Clarke answered with a mirthless laugh, “are really low.”

Clarke is especially pessimistic that the Trump administration will do anything effective to combat the threats in cyberspace, especially since the president’s pugnacious national security adviser, John Bolton, last year eliminated the position of cybersecurity coordinator on the National Security Council—in part because he didn’t want any challenges to his authority.

“There are isolated pockets of career civil servants who are trying,” Clarke said. “There are some people in Homeland Security who are trying—some people at the FBI, some people at NSA, some people at Cyber Command [an agency of the Defense Department]. But what we don’t have is an executive order, a national-security directive. We don’t have anybody in the White House who is a single coordinator of a response. We don’t have a request for money—in fact quite the opposite. The administration is telling [Senate Majority Leader] Mitch McConnell to oppose more money for cybersecurity in the election process.”

On the bright side, however, Clarke said he was heartened recently when Trump rejected Bolton’s advice to bomb Iran to retaliate for attacks on oil tankers, and instead listened to Fox News host Tucker Carlson’s pleas to stand down.

“I know John pretty well,” Clarke said, going back to their days when both worked in the State Department under Ronald Reagan and Bolton was an assistant secretary. “He’s aggressive, he’s iconoclastic, and he likes to think things up and damn the consequences. That’s OK when you’re an assistant secretary of state, but not when you’re national security adviser.”

Unable to suppress a laugh, Clarke added, “I loved the fact that when Trump went to North Korea last month, he took Tucker Carlson with him and sent John Bolton to Mongolia. It was very funny.”

Like Bolton, but for different reasons, Clarke is very nearly a household name. His unhappy tenure as Bush 43’s counterterrorism adviser in the months before 9/11 earned him a portrayal by actor Michael Stuhlbarg in the Hulu miniseries The Looming Tower.

“I’m probably the wrong person to ask about how he portrayed me, but everybody I know who knows me—and certainly everybody I know who worked with me in those days—said ‘you were a much stronger, louder, more bossy kind of person than he portrayed, and more in charge than he portrayed. I think that’s probably right.”

A former Republican who supported Barack Obama’s 2008 presidential campaign and later served the 44th president as an ex-officio cybersecurity expert, Clarke is backing South Bend, Indiana, Mayor Pete Buttigieg this time around.

“The only candidate who I have noticed mentions cybersecurity pretty regularly is Pete,” Clarke said. “Maybe that’s because I’m advising him.”

Clarke said he has been volunteering as a Buttigieg policy adviser for the past six weeks, and has already “maxed out” in his contributions (the federally allowable figure is $2,800) to the 37-year-old mayor’s Democratic primary race.

“A friend said, ‘You gotta read his book,’ and I was like, ugh, fuck, I got so many goddamn books to read,” Clarke said, by way of explaining his enthusiasm for Buttigieg, whose memoir, The Shortest Way Home, was published in February. “But I read the book and I was like ‘Whoa! Did this guy actually write this?’ And I said to myself, this has got to be a ghostwriter—so let me go hear him speak.”

Clarke ultimately attended a Buttigieg campaign event in Washington, D.C. “It was pretty clear he wrote the book, and pretty clear that he is a very bright fellow, and has emotional intelligence, and thinks systematically,” Clarke said, recalling his reaction. “Just on sheer intelligence alone, he’s undoubtedly in a class by himself.

Clarke, who is 68, continued: “At my stage in life, I’m more concerned about who should be president than who’s gonna win. And I said that back when Obama was running in ’07, when I read his books and went to meet with him, and I was blown away.” Clarke said he pledged his support to the freshman Illinois senator as “a voice in my head said ‘but you have no chance of winning.’… It’s the same this year.”

Clarke predicted that Buttigieg’s public profile as an out-gay man, who happens to be married to another man, won’t hurt his presidential prospects.

“I think the country’s ready for it, but it’s more the fact that he’s a small-town mayor with no federal experience and no national experience,” he said about Buttigieg’s political handicaps. “I never heard of him before six months ago. So he’s got a much harder row to hoe than people who are senators and people who have run for president before. I think if everybody started with a clean slate equally, he’d have a helluva chance, and the fact that he’s raised more money than anybody else in the last quarter [$24.8 million] means that he still has a chance.”

Clarke’s The Fifth Domain, co-authored with former Obama administration cybersecurity adviser Robert Knake, is a comprehensive survey of the threats from this country’s four most determined cyberwar adversaries—Russia, China, Iran and North Korea—and how the government and U.S. companies can successfully defend against them.

The threat is more far-reaching than simply a foreign power such as Russia meddling in American democracy by hacking into private emails and balloting systems, while deploying bots to target persuadable swing-state voters with potent lies.

“I rank the cyber threat right under global warming and climate change” as the nation’s most pressing challenge, Clarke said, “because it touches everything. It touches health care. It touches the economy. It touches the military. It has become a pervasive problem throughout everything we do.”

Calling Russia, China, Iran, and North Korea the United States’ “Big Four” cyber enemies, Clarke said, “When you look at the annual threat briefing that the intelligence agencies give to the Congress in open session, those are the four they mention. But it’s very interesting what they said this year… They said Russia is in the controls of our power grid and could cause outages in parts of the country. China is in the controls of our gas pipeline system, and could cause outages. Iran could attack U.S. companies and wipe all data from their networks. Those are rather specific, I thought.”

Meanwhile, North Korea—infamous for hacking into the emails of Sony movie executives five years ago (payback for a 2014 comedy in which a Kim Jong Un character is assassinated)—regularly invades the computer networks of banks “to steal money,” Clarke said. “The North Koreans are different from the other three in one respect: The North Korean government hacks for money—it’s a major source of revenue for them—whereas the other three hack for espionage purposes.”

Clarke, who these days earns his living as a corporate cybersecurity consultant, has been a member of the national-security establishment at least since 1985, when he was appointed deputy assistant secretary of state for intelligence during the Reagan administration. But he is probably best known as that rare government official who has publicly apologized for official failure—in his case, the government’s failure to prevent al Qaeda’s hijacking of commercial airliners to attack the Twin Towers and the Pentagon and kill nearly 3,000 people.

Testifying before the 9/11 Commission in March 2004, Clarke famously called the public hearing “a forum where I can apologize to the loved ones of the victims of 9/11,” and added: “To them who are here in the room, to those who are watching on television, your government failed you, those entrusted with protecting you failed you, and I failed you. We tried hard, but that doesn’t matter because we failed. And for that failure, I would ask—once all the facts are out—for your understanding and for your forgiveness.”

Never mind that Clarke, as Bush 43’s counterterrorism adviser, had repeatedly warned the president’s national security adviser, Condoleezza Rice, that the U.S. intelligence community was picking up alarming chatter that indicated something imminent being planned in the months-long run-up to 9/11; Rice and her deputy, Stephen Hadley, who blocked Clarke’s access to the president, persistently ignored Clarke’s urgent requests for high-level meetings to respond to the threat.

“It was just horrifying,” Clarke said, recalling his stint under Bush 43, “because he clearly was not too bright, and then he had such an inferiority complex. It didn’t work out very well…”

Clarke, who left the Bush White House in 2003, continued: “They made enormous mistakes before and after 9/11. The mistakes after 9/11 were probably even worse. The Iraq War is an unforgivable mistake that destroyed the lives of many Iraqis and many Americans, and our children and grandchildren will be paying for it for many years to come.”

As assistant secretary of state for political-military affairs, Clarke had worked closely with Bush 43’s father, President George H.W. Bush, to muster international support for the first Gulf War.

“Bush 41 was a very good national-security president,” Clarke said. “He knew how the machinery worked, and he was good at working inside it. He respected it, he respected the system, he respected the people. And he achieved incredible results. The way in which he ended the Cold War was perfect, spot-on. And the way in which he conducted the first Gulf War was damned-near perfect. If you were electing a president for national security alone, he would have been perfect. He didn’t care about much else, unfortunately.”

Clarke voted for Bill Clinton in 1992, even though a Clinton presidency meant he’d probably lose his job. Much to his surprise, Clinton not only kept him on, he elevated Clarke to the White House, where he served on the National Security Council and enjoyed Cabinet-level access to the president as Clinton’s point man for security, infrastructure protection, and counterterrorism.

“I loved Bill Clinton,” Clarke said, and Clinton has returned the favor, effusively blurbing Clarke’s latest book. “The guy was and is incredibly smart and curious—really a rare breed. He’s a lot like Pete Buttigieg in a way.”