But that begs the question, has the US invaded Canada or Mexico recently? It's relations with Canada are good, and with Mexico, which is a bit of a governmental head case, reasonable.
Russian is reaping from its immediate neighbours what it has sown
It's more of a question would the U.S. invade IF Russia put some army bases there or if Mexico/Canada said they will work with the Russians (hitchens point).
Isn't that entirely why Cuba was invaded (i think) cause they were cosying up too much with the soviet union?