Residents of Crimea voted over the weekend on whether they would remain an autonomous region of Ukraine or join the Russian Federation. In so doing, they joined a number of countries and regions — including recently Scotland, Catalonia and Venice — that are seeking to secede from what they view as unresponsive or oppressive governments.

These latter three are proceeding without much notice, while the overwhelming Crimea vote to secede from Ukraine has incensed U.S. and European Union officials, and has led NATO closer to conflict with Russia than since the height of the Cold War.

What's the big deal? Opponents of the Crimea vote like to point to the illegality of the referendum. But self-determination is a centerpiece of international law. Article I of the United Nations Charter points out clearly that the purpose of the U.N. is to "develop friendly relations among nations based on respect for the principle of equal rights and self-determination of peoples."