Originally Posted by
Thekri
The bigger problem is resources in a long war scenario. While the US could become reasonably self-efficient with just control of North America, it would take a LOT of work to get that way. And its economy wouldn't grow, it would slowly shrink away, while the rest of the world would continue to prosper quite well. Yes, nobody could really decisively invade, but at a certain point air attacks would get unmanageable. When the world's large economies actually got into high gear in military production, the US naval dominance could disappear fast. The US has huge advantages in a short war, but a long war is unwinnable, at least alone.
The real strength of the US military is the friends we made along the way. That is tongue in cheek, but absolutely true. The US is the only nation on the planet that still maintains a level expeditionary mobilization. In other words, it is the only military that can effectively fight a significant size war on another continent. It can do this, and our allies can get away without doing the same, because the US eliminated all its competition by making friends with them all. Truman and Eisenhower were the architects of a world order that saw all the worlds most significant economies formed into a global alliance. This alliance has been amazingly resilient, and has really no parallel in how well everyone has gotten along for so long. The US military isn't built to "Fight the world". It is built to fight alongside the whole world. We integrate British, German, Australian, Japanese, and Canadian forces into our operations smoothly and constantly, because that is how all those militaries are designed to fight. When I was in Afghanistan, at various times I reported to Polish, Romanian, and German officers, all smoothly integrated into our operations. This is nearly totally frictionless.
I do get the scenario is a thought exercise, but the reality is that our fate is intertwined with our allies. We couldn't really stand on our own either economically or militarily, at least not forever.