alt Hacker NewsFHSS[1] has made jamming difficult in US military communications for decades. It doesn’t make it impossible but jamming the entire spectrum is nearly impossible at scale for almost everyone. At best it would affect small areas until the US sent rf seeking missiles (HARM are designed for this) at the jammer source. Also note that modern satcom like Starlink uses AESA digital phased array antennas much like a F35’s radar. It’s so much more complex than legacy analog stuff.
[1] https://en.m.wikipedia.org/wiki/Frequency-hopping_spread_spe...
It’s easily possible to jam a frequency spread signal from a satellite, assuming you can get the directionality right (i.e. you need to be in the beam of whoever you’re trying to jam, or you’ll need even more power to overcome their receive directionality, which is never perfect).
Signal strength (satellites are power constrained) and distances involved are tough.
GPS uses frequency spreading too, and locally jamming that (even the military version with a secret/unpredictable spreading code) is trivial, for example.