The State Dept issued a public warning two weeks ahead. Or course the Russians knew at least that much, if not from their own intel they can read our public statements. How much more detail the State Dept had or could have shared is obviously unknown.
But as for establishing “innocence” it can just as easily be turned around to claim evidence of guilt or complicity. “The Americans knew it and didn’t warn us” or even “The Americans planned this and warned their own people to get out” like all those conspiracy theories on 9-11 about people being warned ahead of time.
Going back....Looks like we were constantly issuing “get out of Town” advisory going back a couple years.