The January 2017 report, called an Intelligence Community Assessment, followed months of leaks to the media that had falsely suggested illicit ties between the Trump campaign and the Kremlin while also revealing that such contacts were the subject of a federal investigation. Its release cast a pall of suspicion over Trump just days before he took office, setting the tone for the unfounded allegations of conspiracy and treason that have engulfed his first term.

What was Brennan's motive? Among the possibilities is hostility within his camp toward Michael Flynn (foreground), Trump's future reform-minded national security adviser.

The ICA's blockbuster finding was presented to the public as the consensus view of the nation's intelligence community. As events have unfolded, however, it now seems apparent that the report was largely the work of one agency, the CIA, and overseen by one man, then-Director John Brennan, who closely directed its drafting and publication with a small group of hand-picked analysts.