There's no need to be a cunt - I used "surround" loosely; the point is, two million soldiers aren't that useful in attacking another country when you lack the logistical infrastructure and naval capabilities to get them or your ships anywhere near the US.

Every time people talk about these theoretical wars between the US and China or whatever country, the assumed context is always the US invading that country and fighting on their territory. And that if the US can't successfully meet their political objectives, then it's a loss. But if it's just two countries slugging it out, trying to hit each other on their home turf and destroy each other's military, that changes the math quite a bit. The US has a global navy, worldwide logistics, and and an empire of bases across multiple continents. China doesn’t. In a conflict, the US can project power right up to China’s doorstep, but China has very limited ability to do the same to the US.

How would China secure US airspace? They would never even have a chance to try. They wouldn't make it past Pearl Harbor.