The one thing I haven't seen mentioned once, which has kind of surprised me, is that the United States has the greatest force projection of any nation in recorded history. Nearly our entire military can strike anywhere, and maintain sustained combat in those areas indefinately. No other nation can boast this (especially nations like Russia and China which have superior defences [in numbers], but no ability to push that power on to other land masses than their own) although a few of the other 1st world nations like Brittain and France can move large amounts of very well trained soldiers to trouble areas.
Also, as far as conventional warfare is concerned, the united states does hold significant advantages in large scale scenarios, for instance, our Blue Water Navy is the strongest on earth (if not, it is certainly in the top 3), but we would fare badly in Brown Water engagements. Our Main battle tank has proven far superior to every counterpart manfactured against it, specifically the Russian made T-80 and T-90, who's kill/loss ratio against the Abrams is utterly appalling. Again though, our armed ground forces suffer badly against guerilla tactics and Democratic knee capping. I find it ironic that the party trying so hard to pull our boys home are the ones that voted down all the armor and weapons that our military was claiming costs them lives, for instance, better body armor, and armor on the humvees. Guess the blood on their hands got a little to high, after all it's one thing to kill the enemy, another entirely to kill your neighbor's kid.
Our Air Force, however, has had the advantage since Vietnam, the lessons of that war were hard learned in the air (never go up without your knife). Since then, our BVR engagement capabilities have proven devistating to soviet era craft, and the numbers will only get worse with the current generation of stealth fighters. Though I will admit, the US stockpile of short range IR weapons, like the AIM-9 sidewinder, are badly in need of an overhaul. The AIM-9X will be a godsend for us, and unabridged horror for the poor sap who manages to get in on a F-22 or F-35.