To begin with, I believe that all nations -- strong and weak alike -- must adhere to standards that govern the use of force. I -- like any head of state -- reserve the right to act unilaterally if necessary to defend my nation. Nevertheless, I am convinced that adhering to standards strengthens those who do, and isolates -- and weakens -- those who don't.
The world rallied around America after the 9/11 attacks, and continues to support our efforts in Afghanistan, because of the horror of those senseless attacks and the recognized principle of self-defense. Likewise, the world recognized the need to confront Saddam Hussein when he invaded Kuwait -- a consensus that sent a clear message to all about the cost of aggression.
Furthermore, America cannot insist that others follow the rules of the road if we refuse to follow them ourselves. For when we don't, our action can appear arbitrary, and undercut the legitimacy of future intervention -- no matter how justified.