Watch: Ex-CIA director explains how Trump is abnormal and why he 'won't bite his tongue' any longer
Former CIA director John Brennan on MSNBC/Screenshot

Former CIA director John Brennan on Friday published his first op-ed since leaving government in the Washington Post to explain why so many former national security and intelligence officials have taken to speaking out against President Donald Trump. In conversation with hosts on MSNBC's Morning Joe, he further detailed why he's breaking the intelligence community's norms of silence.

"Why do you feel the need to speak out so strongly, so aggressively about what you see happening in the Trump administration and in the intel community?" host Joe Scarborough asked.

Brennan detailed a laundry list of issues with Trump: "because of the abnormal and aberrant behavior of Mr. Trump that very much concerns us because of the negative impact we believe it is having on our national security," as well as the "bad signal that it sends to our young Americans, as I say in the op-ed, who look upon him as somebody who should be emulated as the most powerful position in the world, the president of the United States."

"His continual lying as well as lack of ethics as well as lack of rigor in terms of the policies that he pursues" also concern the former CIA director and his ilk. 

"It is abnormal for us to speak out as critically and vocally as we have," Brennan said, "but these are abnormal times and he is an abnormal president."

"He's an aberration, and not in a good way," the former CIA director said. "That's what gives us the motivation to speak out."

Watch below, via MSNBC: