I agree with Nugax.
Since we're talking about AH here, you would have to make the US more powerful then it was inn the '90s. Since it was basically the only Superpower, there isn't much you can do to make it more powerful short of makinng other nations actually subservient to America, by possession or vassalage. That would require a largely different US, with a deeply ingrained "Manifest Destiny 2.0" and an insane amount of luck. Such a nation would would truly be a Hegemon, which may not be that good for the States-in addition to the moral dimension, I personally doubt the ability of such a state to survive indefinately. Then again, as is happening OTL, this will allow other states like China and India to emerge as powers-but still, OTL is probably the best-case scenario for the US.