Not GP but modern GPS / GNSS manufacturers intentionally do not allow their devices to function over some speed (1000 mph or something like that).
So they won't work on warheads as part of a guidance system.
So they won't work on warheads as part of a guidance system.
Ultimately these kinds of regulations are fairly silly because a sufficiently determined smart person can recreate the covered technologies from scratch, but here we are.
But when the details of these things are published or otherwise made openly available, it doesn't take nearly as many smarts to duplicate these accomplishments.
Quite often, that's good: It's easy for a dullard like me to build a circuit or to re-use some clever assembler code when someone else has published it for my own tinkering around the house. In this way, it's a pretty great world to live in; it is often very simple to stand on the shoulders of giants and get some things done that I could probably never do on my own.
But sometimes, that's bad: We don't live in a perfect world. Enemies exist. Things like ITAR can't prevent a sufficiently smart person from doing anything, but they do make it a lot harder for them to get started.