Former President Donald Trump allegedly admired dictators-including Adolf Hitler, an upcoming book by CNN’s Jim Sciutto reveals.

The book titled “The Return of Great Powers” set to be released on Tuesday looks into the inside workings of the Trump White House. Sciutto has in-depth conversations with senior officials in the administration, including Trump’s former Chief of Staff John Kelly,

“My theory on why he likes the dictators so much is that’s who he is,” Kelly said, according to a CNN article published Monday about the upcoming book.

“He said, ‘Well, but Hitler did some good things.’ I said, ‘Well, what?’ And he said, ‘Well, [Hitler] rebuilt the economy.’ But what did he do with that rebuilt economy? He turned it against his own people and against the world. And I said, ‘Sir, you can never say anything good about the guy. Nothing,’” Kelly noted. “I mean, Mussolini was a great guy in comparison.”

“It’s pretty hard to believe he missed the Holocaust, though, and pretty hard to understand how he missed the 400,000 American GIs that were killed in the European theater,” Kelly added.

Kelly proposes a theory that Trump was shocked at the limitations imposed on him by the Constitution. Trump, accustomed to the executive independence of a business leader, found the checks and balances of the American political system to be a burden to his preferred mode of governance.