He wrote on Thursday Trump was "becoming more desperate to protect himself and those close to him" as the Russian Federation investigation continues. The same apparently is true of Comey, according to his friend Ben Wittes, because he was also fired.
Mr Brennan claimed on Twitter after Ms Sanders's announcement that Mr Trump sought to "suppress freedom of speech and punish critics".
Brennan, who has briefed Republican and Democratic presidents, could now lose access to classified information - a courtesy usually afforded to former senior officials of all political stripes. "I will not relent", wrote Brennan.
Some, like the Washington Post's Greg Sargent, interpreted this to mean that punishing Brennan - and threatening to revoke the clearance of other critical former officials - was really about "striking a political blow against" Special Counsel Robert Mueller's investigation.
"It's unprecedented. I don't know of a case where this has ever been done in the past", Clapper said in a CNN interview after the announcement, adding that typically the Central Intelligence Agency would handle decisions to revoke security clearances, rather than the White House or the President directly.
Brennan called Trump's behavior at a summit with Russian President Vladimir Putin "nothing short of treasonous".
Former high-ranking government employees can in some cases ask for and receive a security briefing on a certain subject. They nearly never do, and the smart money says that, if they do, they will lose - largely because of the virtually total support of the Establishment media for the Deep State. "For as long as I have been aware, which is probably two decades, former senior officials have kept their clearances". "And in fact when I made a decision to just do it, I said to myself, I said, you know, this Russian Federation thing with Trump and Russian Federation is a made-up story; it's an excuse by the Democrats for having lost an election that they should have won", Trump said back in May 2017.More news: Brooks Koepka holds off Tiger Woods, Adam Scott to win PGA Championship
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He also described the action was something he had seen from "foreign tyrants, despots, and autocrats" throughout his career. Those persons were placed on notice that their clearances might be revoked or non-renewed. Rand Paul, R-Kentucky, in a tweet.
Did Brennan then become part of a group organized to frustrate Donald Trump's candidacy?
John Brennan has been an outspoken critic of the president. It's risky, because it the president is ratcheting up tension in an already hard relationship with his intelligence community.
He said in a statement: "Once again this president is sending a message that he will punish people who disagree with him and reward those who praise him".
Former CIA director John Brennan had his security clearance revoked on Wednesday.
He went on to suggest he's reviewing the security clearance of other critics - James Clapper, James Comey, Michael Hayden, Sally Yates, Susan Rice, Andrew McCabe, Peter Strzok, Lisa Page, and Bruce Ohr - simply because he's decided that they're bad people. "The CIA director or DNI should speak up on this one". Bob Corker, R-Tenn., saying, "Unless there's something tangible that I'm unaware of, it just, as I've said before, feels like a banana republic kind of thing".