Respect for sovereignty can be an effective tool to manage relations between states, drawing boundaries of acceptable behavior. But there are also clear costs of respecting sovereignty. A foreign policy based on a principled defense of sovereignty can be, in fact, morally wrong, politically illegitimate, and strategically dangerous. This does not mean that sovereignty should be broken wantonly, but only that prudential judgment must be exercised to weigh the costs and benefits of respecting the sovereignty of a state. In the end, our security and our values, not the principle of sovereignty, should be the metric by which we should judge the necessity and legitimacy of U.S. actions.