The debate on the origins of the Russia-Ukraine War is at an impasse. Many prominent realist scholars argue that Russia’s government chose to invade Ukraine as a last resort to reverse Ukraine’s Euro-Atlantic integration, which it viewed as a major or “existential” national security threat. Critics of this contend that Ukrainian accession did not seriously threaten Russian security, and that Putin launched the invasion in the hope of achieving one or more nonsecurity objectives. This article surveys the current debate, before evaluating one of Moscow’s key stated security concerns. It then identifies four empirical issues on which security and nonsecurity accounts make substantially different predictions. It concludes that in each case, the available evidence is difficult to reconcile with a primarily security-seeking interpretation of the Russian government’s war aims.