It's pretty rich that you evidently think lardass middle-aged Texans with guns are in any way nearly as self-sufficient as the Taliban. The US lost in Afghanistan and Vietnam because the opposition in those countries was willing and able to wait out the US. In this hypothetical the opposite would apply; the US would be more than happy to never fire a single shot and to simply isolate Texas from the rest of the world and watch it fall apart as its utterly interdependent economy collapsed.