Fire and Fury: Inside the Trump White House by Michael Wolff:
Within the West Wing there was much replaying of alternative scenarios. If you wanted to get rid of Comey, there were surely politic ways of doing it—which had in fact been suggested to Trump. (A curious one—an idea that later would seem ironic—was to get rid of General Kelly at Homeland Security and move Comey into that job.) But the point really was that Trump had wanted to confront and humiliate the FBI director. Cruelty was a Trump attribute.
The firing had been carried out publicly and in front of his family—catching Comey entirely off guard as he gave a speech in California. Then the president had further personalized the blow with an ad hominem attack on the director, suggesting that the FBI itself was on Trump’s side and that it, too, had only contempt for Comey.
The next day, as though to further emphasize and delight in both the insult and his personal impunity, the president met with Russian bigwigs in the Oval Office, including Russia’s Ambassador Kislyak, the very focus of much of the Trump-Russia investigation. To the Russians he said: “I just fired the head of the FBI. He was crazy, a real nut job. I faced great pressure because of Russia. That’s taken off.” Then, to boot, he revealed information supplied to the United State by Israel from its agent in place in Syria about ISIS using laptops to smuggle bombs onto airlines—revealing enough information to compromise the Israeli agent. (This incident did not help Trump’s reputation in intelligence circles, since, in spycraft, human sources are to be protected above all other secrets.)
“It’s Trump,” said Bannon. “He thinks he can fire the FBI.”