GPS is one of the core technologies in western defense.
So influencing it has for sure a lot of attraction for any potential adversary.
Brute force direct jamming might be the easiest thing to deal with. At least you notice that you have a problem.
A more nastier way will be some kind of deception. I remember reading once a article about jamming that said "the most effective jamming is when the target doesn't know its being jammed".
For example many guided weapons rely on GPS guidance. i am not confident that these computer are smart enough to detect some subtitle jamming that messes up thier guidance just enough to miss thier target by lets say a mile.