> In free press societies, you need the will of the people to go to war.
Sure. And this consent can be produced when there is a need for it. “Proof” is not the missing component.
That American basketball player who the Russians detained? Casus belli. The cyber attacks? Casus belli. Shelled civilians? Casus belli. The NATO country cargo ships which got hit and sunk? Casus belli.
These are just the ones I can think of. A proper state aparatus can come up with many more and probably even better ones. Government officials will leak the background, solemn faced politicians will demand justice while friendly journalist will write up the whole thing in the most hearth wrenching way. If they want to they can.
So why do they don’t want to? Is it because the Russian army is so powerfull that we think we can’t overpower them? No. Is it because the Russian air defences are so advanced that they cannot be picked apart? No. So what is it which makes the west avoid a direct confrontation with Russia? Why are they doing this strange dance of supplying weapons to Ukraine and hurting Russia with sanctions, but not directly engaging with them troop-to-troop? It’s the Russian nukes.
> You misunderstood, or simply ignored the word “public”.
I don’t think so. You won’t “prove” anything to the public through detailed technological explanations. A fig leaf of deniability might be an interesting roadblock in a criminal prosecution where things have to be proven “beyond a reasonable doubt”. In a situation where there is a governmental will to engage in a peacekeeping mission (read: send troops to fck the Russians up) the evidentiary level is “can we find an authorative sounding voice in the whole government who can tell the right sod story to enough guilable journalist to sell the people on it”. That is such a low level of “proof” that one might as well assume it can be met nearly always.
Journalist won’t pour over the attack binaries using Ghidra to make an assesment about the relative probabilities that it has the signatures of being created by this or that advanced persistent threat group. The ones who would demand that level of rigour before publishing won’t get the scoop. The ones who are selected to spread the message will have a lovely hour with a very charismatic “expert” who will walk them through just enough of the detail to sound right but not to get bogged down in unnecesary complications. This chat will get translated into a single line in their article, maybe something like “experts at the National Security Agency matched the unique signatures of the cyberweapon to the advanced persistent threat group Tippsy Bears, a known front of the Russian Federation.” Followed by two pages of hearth wrenching human angle story about innocents suffering needlesly. That is the “proof” the public might get.