Not really. Taking out the US Navstar/GPS satellites wouldn't be very effective unless you coordinated to take out a lot of them at once because there's a fair

Not really. Taking out the US Navstar/GPS satellites wouldn't be very effective unless you coordinated to take out a lot of them at once because there's a fair amount of redundancy in them. Also, they're in MEO at ~20k km, not where there's a lot of other stuff (including antisatellite weapons). I don't know enough about orbital mechanics to know if antisatellite weapons in geosynchronous orbits can easily attack things in MEO but I know that you can't do it very quickly from LEO unless you have significant (ie visible from the ground) fuel/engines already in LEO. Also, there are QZSS, Beidou, Galileo, and GLONASS now too. You'd have to take out multiple systems (or convince their operators to geofence) to actually deny all useful location signals to an area. This is rapidly becoming a project that is beyond the capabilities of most single countries, given the number of different systems, number of different satellites, number of different frequencies, and number of different orbits.