The Obama administration has prepared a nice Christmas gift for the post-Soviet bloc: a declassified map of the targets of nuclear bombs, see e.g.
The 800-page 1959 document (above the notes, 8 chapters) lists the targets in China, the Soviet Union, and Eastern Europe. Moscow, Leningrad, Berlin, and Prague had 179, 145, 91, and 69 targets, respectively.
Barack Obama has pointed out that "the Eastern European nations are not as bad as Putin's Russia" so the plans "only" use smaller nuclear bombs equivalent to 130-600 Hiroshimas each. "But you should better listen to my great friend and ambassador in your statelet, Andy Schapiro, to learn how to behave, what gay pride parades you should attend, and how to become safer," Obama told his Czech friends. ;-)
Even though the bombs for Czechoslovakia "only" had the power of 130-600 Hiroshimas (they were weaker than the for-Soviet bombs for psychological reasons), the map was rather rich:
Via Mapy.CZ and David Ryneš.
You may see that after a dozen of nuclear blasts with the combined force of thousands of Hiroshimas, Prague – the target #61 – would be over. And so would be some other places – like the Northwest coal-driven areas of the Sudetenland and the vicinity of Ostrava. A nuclear bomb would also land in Líně/Lazily, now a non-public international airport 5 miles Southwest from Pilsen. I suspect it would be enough to "finish" most of the Pilsen's population, too. That was a pretty bitter evolution a decade after the wonderfully friendly encounter of the U.S. troops and the local population of Pilsen.
Thankfully, as all of us know, the threat of the mutually assured destruction had the opposite effect – wonderful 70+ years without a major war. But the plans did exist and were treated seriously. I view them as rather barbarian plans. For the Nazis, the victims of the Holocaust were individual lines in the to-be-destroyed lists. In these nuclear war plans, it was whole cities that were assigned a line in the to-be-destroyed lists. Most of the Sudeten Germans genuinely liked the land where they had lived – and even the rest of Bohemia. But the U.S. nuclear planners didn't care about those areas.
There may have been reasons to think in this "big way" but I find the magnitude and the detailed aspects of the philosophy of this nuclear Holocaust deeply unethical. Recall that the Japanese were pretty fanatical but 2 nuclear bombs were enough to change their minds. Would it really be necessary to destroy hundreds of larger targets in order to change the much more pragmatic and pro-life communist opponent's mind? I think that the answer is obviously No. In fact, I am pretty sure that you wouldn't have to bomb any targets outside the Soviet Union at all e.g. for the Czechs to switch the sides. It was mostly a coincidence that we (and a few others) ended in the Soviet bloc. The outcome could be very different if the U.S. army took Prague which it could and should have.
Also, I dislike the pre-planned order of the blasts. A nuclear bomb should be a response to a gross violation of some existentially important principles. And the place where the nuclear explosion emerges should somewhat correspond to the actual hypothetical sin that was made. Or it should be optimized to prevent similar sins in the future. The Nazis have flattened and exterminated the villages of Lidice and Ležáky after reports that the inhabitants had something to do with the realization of the 1942 execution of the blonde beast of Prague, Reinhard Heydrich (one of the main authors of the Holocaust and the Reichsprotektor in Bohemia in Moravia), by the London-based Czechoslovak government. The "guilt" of the village people was based on bogus intelligence and the raid was obviously terrifyingly inhuman but at least they tried to be somewhat surgical in their genocide.
The U.S. nuclear plans from the 1950s were not surgical at all. They were just meant to exterminate tens of millions of people whose only guilt was – at least in many cases – that they ended up on the Eastern side of the Iron Curtain. I sincerely want to believe that this kind of philosophy is no longer present in the U.S. – or other military powers. Communism was a very bad system but it wasn't a reason to destroy and exterminate 1/2 of the world.
If you need to exterminate 1/2 of the mankind in order to make the world compatible with your ideas about the right society, maybe it is you who is the main problem.