California has no oil? You might want to check on that. California actually ranks just behind Alaska for oil production.
Outside Bakersfield.
No need for armed forces. No need for anything.
They have no oil. Cut them off. They starve in a few weeks as food can’t move.
Then there is that problem of being cut off from the Federal Reserve and any source of money.
The left holds both coasts and most of the ports. They’d also retain most of the Air Force and nearly all the Navy. The South lost the Civil War because its commerce was cut off. That might well happen in a second civil war with the same outcome. The west coast especially could probably count on Chinese and even Mexican aid. Europe too would be mainly sympathetic to to the seceding states. Russia and the Islamic world ditto. Unless the left could be crushed quickly they being more ruthless than the right would consolidate power in their areas very quickly and be able to put forces in the field more rapidly utilizing a more highly developed infrastructure.
California has no oil? You might want to check on that. California actually ranks just behind Alaska for oil production.
Outside Bakersfield.
You’ll have to blockade the ports !
The Chines will rush food & oil there even if it means starving and damaging their own economy. They’ve done this before to gain what they think is some “foreign policy advantage”. For example Mao basically shipped his entire “economy” to the then USSR to gain its cooperation in building a nuclear weapons program.
It is a coastal state and can get all the food they want from other counties and Mexico. Are you suggesting a blockade?