chose to support the Americans. They did it because it was in THEIR interests, so their involvement became a resumption of the conflict of the 1750s, not that this has anything to do with larger point.

No, nuclear weapons did not exist in the 18th Century. They did exist in the 20th Century, during superpower proxy struggles in Korea, Viet Nam, Cuba, and Central America. The point being, there have been lots of times in the recent past where the shadow of nuclear war has been in the background and that has not deterred from defending democracy or human rights, sometimes even to the point breaking off relations or calling some country the Evil Empire. As a matter of fact, history has shown us that weakness in the face of aggression is much more dangerous than confronting it honestly.