>would be easily able to disassemble the weapons, reverse engineer the connections to the devices that initiate the detonation and substitute the control units

>would be easily able to disassemble the weapons, reverse engineer the connections to the devices that initiate the detonation and substitute the control units in order to gain operational control. Such an operation cannot need more than a few months at most. I think you're massively underestimating the effort needed to have operational nuclear weapons. Nuclear missiles aren't like a car that you can just hotwire and jump start and something you can store and forget in their silos for years and then dust them off when you need them, but require constant and ludicrously expensive maintenance to stay operational. First you need to have the rockets well maintained and tested to make sure then can have successful lift-off, then make sure the guidance systems are accurate enough to deliver your payload to the target. Secondly and probably the most difficult, you need the detonation mechanism well maintained and tested, as the nuclear reaction needs super precise timing of the fissile material inside the chamber. Otherwise, even if you're lucky and hit your target, if the nuclear reaction is off, the explosion will be a dud and not cause much damage. This is not something trivial that can be pulled off successfully in a few months notice, but you need a coordinated round the clock, and very costly, national program like the nuclear programs of France, UK, US, etc.