If you think "several" low-yield weapons would kill 10 million Americans, you obviously need a LOT more intellectual exercise.
For all its incalculable evils, the USSR was a "civilized" enemy, and culturally not too far removed from the US. (Closer, in fact, than Western Europe has proven to be.)
Now, here's something to consider: the cold war was expensive, very expensive. And protracted. However, the upside is that it kept us on our toes, and motivated us to build and maintain the strongest military in the world.
So if not for the cold war, we'd be in far worse shape today to deal with terrorists. And regardless of anything else, we'd still have them to deal with. They're a modern day counterpart to the Barbary Pirates (and the islamist rulers who were targetted by the Crusades). Only now, they're living in a world where the stakes are much higher, thanks to the cat being out of the bag with respect to technology.
Finally, the USSR was destined to collapse from its inception, because communism is flawed at its root. There's hope of a bright future for the US and Russia, as the latter joins the West (even as the rest of the Western nations seem to be leaving it wholesale).
Here's my recommendation in case of a nuclear "terrorist" attack (quotation marks intentional).Nuke the Axis of Evil. That's the only response that is not appeasement. Yes this is harsh, and very risky. But there are no other real options if one wants to gain the upper hand. All other options and compromises would set us up for losing WW-III.