The Emerging Doctrine of the United States | Stratfor
Jared Sperli stashed this in war
Threats against the United States are many and complex, but Washington's main priority is ensuring that none of those threats challenge its fundamental interests. Somewhat simplistically, this boils down to mitigating threats against U.S. control of the seas by preventing the emergence of a Eurasian power able to marshal resources toward that end. It also includes preventing the development of a substantial intercontinental nuclear capability that could threaten the United States if a country is undeterred by U.S. military power for whatever reason. There are obviously other interests, but certainly these interests are fundamental.
Therefore, U.S. interest in what is happening in the Western Pacific is understandable. But even there, the United States is, at least for now, allowing regional forces to engage each other in a struggle that has not yet affected the area's balance of power. U.S. allies and proxies, including the Philippines, Vietnam and Japan, have been playing chess in the region's seas without a direct imposition of U.S. naval power -- even though such a prospect appears possible.
The roots of this policy lie in Iraq. Iran and Iraq are historical rivals; they fought an extended war in the 1980s with massive casualties. A balance of power existed between the two that neither was comfortable with but that neither could overcome. They contained each other with minimal external involvement.