[VioletlightHeron]

No exploding heads here. The principle is clear: the use of force is only justified either in response to an attack, or with UN sanction.

Somalia, Bosnia, etc.: these were UN-sanctioned uses of force. Gulf War I was UN-sanctioned. NATO ISAF is UN-sanctioned. These were not expressions of American "sovereignty"; the US did not act alone, but first had to secure the support of the international community.

An attack on Iran without UN sanction, to propose an obvious example, would be illegal. The United States has no sovereign right to bomb Iran, or indeed to bomb anyone else.

Frankly, your notion of "sovereignty" is kind of worrisome; it is a perversion and reversal of the actual definition of sovereignty to suggest that the US has the right to ignore the sovereignty of other nations and to violate that sovereignty with military force. Exceptionalism defined, in short.

It is simply laughable to depend on an institution such as the UN to secure the support of the international community for military action when such action can be bottled up in the Security Council by nations with their own agendas. You might as well go out in the street and pray for peace and an end to the genocide in Darfur before Russia and China lift their little pinkie fingers in sympathy. In my opinion, any military action the US undertakes is legally valid if the executive branch presents its case to Congress for support and ratification. The President can make a case to the UN in support, but the US should not be constrained by a lack of action in the UN.