I'm sort of mixed on this...These are the same US intelligence agencies who told us about Iraq and their WMD's...but when it comes to Russia, I don't trust them, I don't like them, and I tend to believe the intelligence agencies when they say Russia interfered with our elections.
Consider that you are "jumping the gun" with your shaky inference in the first sentence, given as much truthful information as possible about the CIA and related agencies.
I think it became apparent that the Bush White House, together with elements of the Pentagon, manipulated the CIA to produce their assessment. One of the many narratives that supports my observation about this is the Valerie Plame episode -- or I suspect, off the cuff, that it does.
For my part, I add my own independent observation -- seldom mentioned anymore since early 2016 -- pertaining to the two school terror hoaxes of 2015-2016. Of course, I add some reasonable inferences to the facts -- for instance, the perpetrators where not Middle Eastern terrorists, whose terrorism only traffics in guaranteed violence as opposed to scare stories or hoaxes.
The hoaxes targeted two of the biggest school districts and their respective voting precincts in the US. They were both solidly "Blue" Democratic districts, each within 50 miles of a previous terror "Ground Zero" -- the Twin towers and San Bernardino. The hoaxes occurred within 30 hours prior to each of two major campaign debates or town-halls.
* The FBI later determined the IP address origin of the e-mails at the center of the hoaxes, with a location in eastern Germany -- coincident with Putin's stomping grounds in his early career, and a center of hot intelligence activity.
Connecting all the other dots in addition to the documents and pronouncements of the intelligence agencies, Trump might get a benefit of the "reasonable doubt" in the criminal justice system which is biased to protect the innocent. But on basic scientific grounds that admit some sliver of uncertainty -- he is "most likely" a Traitor and Enemy of the People.
====================
*To those naïve about propaganda campaigns and psychological warfare, scaring the wits out of parents inclined toward one political party, with inflammatory messages following from a political candidate, would have a predictable effect toward selling the candidate. What was done -- if it was indeed done in that way according to my view of it -- is still terrorism, still a serious crime.