Since Russia invaded Ukraine in 2022, the United States and its allies have searched for the best way to express their horror and dismay. At the level of values, the invasion affronts the core principle of liberal internationalism: the outlawing of wars of aggression. In terms of state interests, the attack on Ukraine exposes much of Europe, especially the former members of the Soviet Union, to a heightened risk of military aggression. Political leaders who had preached pragmatic accommodation with the Putin regime feel betrayed and regret their willingness to rely on Russia to meet their energy needs. Outrage results. In the modern era, states have various measures to express their outrage. The most ancient means for states to do this, and the one against which all other forms of retaliation were measured for much of history, was the use of force ("war"). States would support their armed attacks with economic measures, such as Napoleon's Continental System ("economic sanctions"), when feasible. Another alternative was to privatize retaliation ("private sanctions"). For example, at the time of the founding of the United States, letters of marque and reprisal served as the principal means of privatizing punishment for outrageous conduct. War, either threatened or realized, remained at the center of international conflicts.

Paul B. Stephan, How Do We Express Our Outrage at Russia?, 13 Wake Forest Journal of Law & Policy 189–206 (2023).