. We are being massaged into accepting it by "authority figures" closing ranks to make "authoritative statements." It's just as I suspected.

So US and all EU are part of a conspiracy to persuade us all of Russia's guilt!
Somewhat improbable.

They are better informed than you and from the evidence available to them they conclude that there is" no plausible alternative explanation."

Absolute proof will never be available unless they confess.
To all those governments the evidence is clear.
"Highly likely" is all that can ever be said without a confession.
Doing nothing because of that is not an option.