Worth bearing in mind that we never actually retaliated against the power most closely tied to the attackers.
Most of the people involved were Saudi and they may have had Saudi assistance. Instead we invaded Afghanistan where he was for a period of time, and Iraq who had nothing to do with anything.
So Russia attacking the US could plausibly result in us suspending habeus corpus, abolishing the FDA and spending a decade embroiled in a land war in Azerbaijan.
Smurf yeah we can.