Whats the question ?
FYI In the 70s the missiles we targetted at each other were not very accurate, they in general would only hit an area within 10 miles of their target, the ruskies ICBMS were even worse. Accordingly to ensure each side totally wiped out its targets the warheads they used were in the multi megaton range, the ruskies had some up to 50 megatons, ( 50,000,000 tons of TNT) most our ours were in the multi megaton range as well. This meant to ensure we for example wiped out the Moscow miliary district bases on the edge of the city we would aim 3 or 4 MIRVS ( multiple independant re-entry vehicles) each of multi megaton range which would covert the entire greater moscow city area and everyone in it into a radioactive hole in the ground. The weapons of the time were so huge for example in War Plan UK IIRC they reported that the Ruskies only needed ONE of their nukes to turn ALL of Birmingham into radio active glass, but in fact the soviets had 4 or 5 aimed at our 2nd city.
London as Londonabad was known when it was the English capital had possibly 7 soviet muti megaton warheads aimed at it, almost nothing could survive that cept cockroachs...... ( today that has a certain appeal for me, Londonabad vapourised Hmmmm
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But I digress moving forward to the present modern targetting systems with initertial guidance, multi gyro, and gps systems means that they can literally place a bomb onto individual buildings with unerving accuracy. So we no longer need the huge great city killer bombs, we can now take out an entire military base, manufacting facility, seat of government, oil refinery, rail yard etc with just one Cruise missile or small MIRV using only Kiloton sized weapons ( thousands of tons of TNT instead of millions) OR if small places like command centers government offices are the target with simple MOAB bombs ( Mother of all bombs) a 22,000 pound fuel air bomb.
The problem we have today is that back in the 70s both sides realised that nukes going off on the ground created HUGE amounts of deadly radioactive fallout, but airburst did not. BUT Air burst bombs sent out an EMP burst that spread out over immense distances, often thousands of miles. So today we live in a micro processor , electronic world where almost everything has a circuit or silicone chip or computer controlling it, and if someone set of only 4 small nukes enhanced for EMP at great altitude they would totally destroy every unprotect circuit right across the UK.
Four baby nukes and we are back to the Victorian era, the preppers living near navigable rivers and preserved steam railways will be laughing, as will those who own working horses.