I've always been interested in the Soviet Union (and by extension, the Warsaw Pact) since I lived in Russia while studying for my MA in Soviet military history (specifically the civilian contributions to the Siege of Leningrad). The Cold War saw humanity make the quickest leaps of technological progress we have seen to date - ten years from the time of the first artificial satellite to reach the Moon until Neil Armstrong set the first human foot on a celestial body. We went from rudimentary V-2 rockets in 1945 to nuclear ICBMs. We went from the first model of jet-powered fighters to U-2 spy planes.

How did the invention of things like ICBMs impact the planning of national defense for the two main belligerent alliances in the Cold War? Here are some more specific questions that will help me get the answers I am looking for (also, being a fellow historian, the more primary sources the better!!)

• Can anyone tell me more about the proposed defense plans involving the Fulda Gap? I know that NATO considered that the prime choke point to defending Western Europe from a Soviet tank invasion, but I haven't found much more information on that. Were the NATO plans to hold the Soviets at the Gap or to launch a counter-attack through something like a tactical nuclear weapon (thinking the Davy Crockett nuclear artillery here)?

• How did Civil Defense work for the Soviet Union? I can find absolutely loads of information for the US but finding USSR information is substantially harder since I no longer have access to the (limited) Russian archives. How did the Soviets plan to attempt a defense of their cities and civilians in the event of a nuclear first strike by the US? By and large, I know that civil defense doctrines are more for the population's psychological benefit, but did the Soviets have anything like Duck & Cover or other similar programs?

• What kind of Last-Resort weapons were planned or in existence at the time of the USSR's dissolution? I know about the Dead Hand/Perimeter system, which is supposedly still receiving system upgrades (I saw what I believed to be the radar stations for it when I was travelling to Moscow), but were there any others besides a generic arsenal launch of ICBMs and strategic long-range bombers and MRBMs launched from subs?

• Some of the planned US weapons were absolutely insane. Rods from God, the Project Pluto nuclear ramjet that would power ballistic missiles while spraying everything below it with radiation from its unshielded reactor, which was part of the SLAM (Supersonic Low Altitude Missile) project. SLAM itself would carry a payload of multiple nuclear warheads, and coupled with the Pluto ramjet, would circle the planet dropping the payloads on targets before proceeding to fly over populated areas for several weeks, irradiating as much enemy territory as possible. Keep in mind that SLAM was also travelling at supersonic speeds so in addition to the radiation, the shock waves would also be damaging to the enemy. Did the Soviets have anything on the order of this magnitude except Perimeter? Obviously the US never proceeded with developing this project beyond a prototype, but did the USSR have anything like it planned? What were some of the more extreme, crazier defense plans for the Soviets?

Sorry for the giant wall of text! I have been waiting to post this until I felt I had enough questions to warrant a decent discussion, and I tried to keep it all on-topic as much as possible.