It’s less being stripped, and more a lack of maintenance. Nukes have a shelf life. The elements inside then can decay, this means they need replacing. This is a highly specialist job. It’s also expensive, and can only really be cross checked by the same people who do the work (or detonating it).
A modern nuke is FAR from the “bang 2 rocks together” designs that were first designed. For a start, most are fusion devices. Fairly exotic reactions are used to make a small amount of fusion material to go critical. This creates a shaped charge on a fusion core. The compression wave sets fusion happening, which releases 95% of the energy. Most of Russia’s arsenal is of this sort.
The downsides of these is the use of exotic elements. They often have a short half life, e.g. tritium, with 12.5 years. This means they decay. Even worse, some of the byproducts will actually poison the reaction. E.g. Rather than producing a flood of neutrons, they absorb them.
If any of this chain fails, then your fusion nuke becomes, at best, a low yield fission nuke. More likely, it becomes a dirty bomb. It’s still nasty, but not the city destroying terror weapon it would be intended as.