[Rockingham]

Like most complicated mechanical things, nuclear weapons have a limited shelf life and require maintenance and replacement of components and materials that age out. Thus, after enough time, nuclear weapons that are not maintained are no longer operable. Granted, the baseball-sized chunk of fissile material in a backpack nuke would remain dangerous, but at least a nuclear detonation would no longer be possible even if the armament code can be broken or overridden.

[Lazamataz]

Additionally, activation is a challenge, to say the least. If I am not mistaken in my memory of things I have read, some of these weapons have an array of batteries that must remain charged to certain voltages. All of them are (for example) 5 volts, except for one, which is 5.128492395 volts.

And you don't know which one it is.

And you don't know the exact voltage it should be.

And it discharges to an unacceptable voltage after a relatively short time.

And the whole thing is a paperweight without the right array of voltages.