On Friday, President Obama noted that “any violation of Ukraine’s sovereignty and territorial integrity would be deeply destabilizing, which is not in the interests of Ukraine, Russia, or Europe.” But it also matters deeply to the United States of America and the tools Obama hopes to use to resolve this crisis.

Russia is dividing the territory of a nation in Europe, and what happens next is not just about Ukraine but about the future of the post-cold war world order, the institutions that established that order, and the agreements they were built upon.