What if they do know for a fact that it was Russia who did it but won't give it public because that would mean that Article 5 would be activated, but NATO doesn't want to respond starting WW3. Maybe NATO is doing everything to keep the conflict contained in Ukraine because petty soon PUTLER will be no more.
Russia will eventually admit they did it, even though it will take some time.
Just like they admited Katyn eventually
Just like they admited donbas green men
And there are still many actions to be admited:
Malaysian plane in donbas
Bombed buildings in 99 to start 2nd chechen war
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