Russia’s invasion of Georgia is a game changer. This war is part of a Russian strategy of roll-back and regime change on its borders. The more evidence that comes in, the clearer it is becoming that this is a conflict Moscow planned, prepared for and provoked—a trap Tbilisi unfortunately walked into. A core Western assumption since 1991—that Moscow would never again invade its neighbors—has been shattered. As Moscow basks in its moment of nationalistic triumphalism, the West needs to take steps to prevent further Russian moves from spreading instability to others parts of Europe. If they want to contain this crisis, NATO foreign ministers meeting here tomorrow need to focus on two strategic imperatives. The Alliance must take steps to reassure those members fearing Russian pressure that NATO’s mutual-defense commitments are credible and real. And ministers must consider speeding up enlargement plans to lock in stability in the Balkans and bring in Ukraine and the southern Caucasus.