At the time, they showed prima facie evidence of this attack by the Assad regime. You're now referring to additional details that have been released (declassified)—the polit communications.
At the very beginning, releasing that level of detail was absolutely unnecessary. Better to be prudent.
So "big mistake", my ass.
The Trump administration did precisely what was prudent at the time, including providing adequate evidence, and the only "big mistake" is the one the naysayers made when they jumped to conclusions and didn't trust this administration in the first place.
It's ridiculous to think the administration should have released every single intelligence detail right away—such as this one.
The hand-wringers are proven wrong again, and when they are, suddenly it's all about the "big mistake" the administration made by not releasing sensitive information immediately, and a "rift" that thereby resulted.
Bull. The only "rift" was created by the doubting Thomases who disregarded the initial evidence which was perfectly reasonable.
Next time, don't imply that the Secretary of Defense and the President are liars, and maybe there will be less of a "rift".
Or, alternately, maybe next time the administration should just dump all their intelligence immediately and throw caution to the wind...