Dude Cali is shot through with miltary bases. There are 2 USAF bases at least in LA County alone.
You forget that most of the population centers are coastal. Nobody gives af about Lancaster, those mutants are oftentimes proud that they've never been down the 14 to begin with.
San Diego, OC, LA, Santa Barbara, San Fran.
Blockade the coast, really just those towns and Monterey Bay, hold the forts, and cut off water supplies from out of state. Cali would fold without a shot. That state doesn't even have their own fire planes. We load up a lake diver with concrete powder and jam up the Aqueduct up near its source and you're fucked.
You can't even swim in the Salton Sea, much less drink it. And those reserviors drain quickly, just ask the Palisades.
Hasn't a lot of local oil production been shuttered, too? Think Chevron is pissing off 49 states to help out one extremely annoying market during a seige?
We fought a war over secession, putting Republic in your state's name doesn't change that.