NATO's air campaign against Yugoslavia precipitated the most dangerous turn in Russian-Western relations since the early 1980s. Although tensions have eased since the end of the Kosovo war, the anger and suspicion engendered on the Russian side will not easily dissipate. The anger will endure not least because the Russian reaction had little to do with the Serb-Kosovar conflict itself, and much more to do with Russia's growing unease about NATO's post-Cold War transformation: its enlargement and pretensions to act beyond the territory of its members, without an explicit UN mandate. Repairing relations will require political realism in Russia, the absence of a major new crisis in Kosovo, and restraint from NATO.