How many times has the US invaded other countries in the Western Hemisphere? What if Russia tried to intervene in those cases? Of course look how we reacted when the Soviets were putting missiles in Cuba? Why would we expect the Russians to be any different when we are playing in their backyard?
“How many times has the US invaded other countries in the Western Hemisphere?”
In the contemporary time period, I can think of 2 cases: Grenada and Panama.
1. Grenada: American citizens in the medical school were being threatened and roughed up by police from Granada and Cuban military.
We invaded, secured our citizens and found Cuban military and arms all over the island. THEN WE LEFT.
2. Panama: Again, “Dignity Battalions” were beating and shooting at US citizens and military. AGAIN WE LEFT.
RUSSIA: Georgia, Crimea, Ukraine...THEY HAVE NOT LEFT.
Not to mention attempts in the Baltics after the Soviet implosion.