“They came up and talked to me about it and I listened to them because I wanted to make sure I understood exactly what their concerns were,” Mr. Brennan said in the C-SPAN interview. “And I encouraged them to talk to the authors of the assessment and determine if the judgment should stay at high confidence or medium confidence.”
Intelligence agencies characterize their confidence in intelligence typically at three levels: low, moderate or high. High-confidence conclusions typically have multiple sources and draw from different kinds of intelligence, such as electronic intercepts, satellite photos or human sources of information. A moderate, or medium, level of confidence could reflect that the sourcing behind a conclusion could be weaker.
Mr. Brennan declined to discuss the sources behind the judgment that Mr. Putin sought to aid Mr. Trump. But other former officials have said that a C.I.A. informant, who has since been extracted from Russia, was particularly important for making the judgment; because Mr. Putin eschews electronic devices, intercepting his communications is notoriously difficult.
Mr. Brennan said he had been reviewing new intelligence about Russian interference since the summer of 2016 and was steeped in the material. In his conversation with the two senior officials, he realized they may not have seen all of the material that he and the analysts who wrote the initial conclusion had reviewed.
“In my conversation with them, it was apparent to me, and I say in the book, that they had not read all the intelligence that I had read,” Mr. Brennan said. “So my own view was to support the analysts.”
Mr. Brennan’s decision to back the analysts was the right decision, said Michael Morell, a former acting director of the C.I.A.
“I spent 33 years at C.I.A., most of it as an analyst,” Mr. Morrell said. “Director Brennan handled this exactly the right way. At C.I.A., the analysts make the substantive calls, not senior managers.”