This is where Bitcoin (or really anything hard to steal) comes in handy, because it's suddenly a lot less cut and dry that you can just go in with a force and take all the gold.
But if they wanna take the fuel, food, and other resources, yea, they can just do that with a sufficiently powerful force.
There's not much getting around lex talionis aside from making it cheaper and more profitable to acquire through trade rather than through conflict. Trade openly, maintain defenses, and be ready to use them of necessary. True at the individual level all the way up to national.
