If Al Capone, Squizzy Taylor, or any other gangster was walking down the street and saw a young thug attacking an elderly woman i'd say they were still in a moral position to defend them. Either individually or alone. In that case past actions of any of the actors involved wouldn't change the morality of the moment.
Vietnam was a different story than Ukraine is now. After the French lost and left, Vietnam was a full-blown civil war.
Past American invasions and other types of involvements in the other countries in the Americas actually could be seen to justify a Russian invasion of Ukraine. For anyone who saw that American involvement as right, that is. Protection of neighborhood, all that.
I didn't offer any thesis, just stated the way it was, and is.
To be clear i don't see any right in Russia invading Ukraine. Still, i can see some justification for them being worried about further involvement of NATO there. I don't think they will invade.
And so far as far as i know Biden is doing a decent mob on that front. Just as he doing about as good a job as he can on covid.