> ...which is strange, because both the Afghanis and the Iraqis seemed to have made out just fine against Uncle Sam.
Despite the protestations to the contrary from the liberals, neither Iraq nor Afghanistan was faced against the U.S. in total war, and even what little attention the U.S. has paid to those conflicts have resulted in relative disaster for the peoples of both nations.
It is true that defeating a dug-in insurgency is no easy task, but there are examples of it being done in history. Unfortunately the methods required are brutal, far worse than anything the U.S. is likely to stomach doing again.
It's kind of apropos you mention economic dominance though; to the extent that resource rights enter into economic stature, a strong military is essential to stopping wars of conquest before they start.
There's a reason China is building up their military so much, once they are strong enough to engage in 'power projection' of their own then little international laws like UNCLOS will be no impediment to them extracting exclusive resource exploitation rights, and probably without much bloodshed (as long as it remains a regional-only conflict, at least).