alt Hacker NewsUS military gps is encrypted and heavily used FHSS. It is jam resistant, and can’t be jammed without significant expertise and know how.
Russia has some of the best EW chops in the world (after the NSA perhaps), and they struggled to successfully jam Starlink after some defensive work was carried out by SpaceX. They use Starlink in the “sea baby” USVs that attacked Crimea just last night.
https://tech.yahoo.com/general/articles/spacex-spends-signif...
GPS uses DSSS, not FHSS. The military version has a higher processing gain than the civilian signal, but it can still be overpowered by sheer signal strength.
I'm not saying that that's trivial against moving targets in a large area (especially if they can use directional antennas), but it's still very possible. GNSS jamming is a big concern of the militaries of the world, and there's currently somewhat of a renaissance of high-precision inertial navigation systems as a result.
Jamming a stationary satellite terminal, if you can get reasonably close, doesn't seem harder than cutting a fiber (although as a sibling comment has mentioned, jammers have the nice property that communication is restored once they're disabled, unlike damaged cables, so maybe the two can complement each other?)