The greatest threat of nuclear catastrophe that humanity has ever faced is now centered on the Crimean peninsula. In recent months, the Ukrainian government and army have repeatedly vowed to reconquer this territory, which Russia seized and annexed in 2014. The Russian establishment, and most ordinary Russians, for their part believe that holding Crimea is vital to Russian identity and Russia’s position as a great power. As a Russian liberal acquaintance (and no admirer of Putin) told me, “In the last resort, America would use nuclear weapons to save Hawaii and Pearl Harbor, and if we have to, we should use them to save Crimea.”

In the eyes of all the participants in the war, Crimea is freighted with crucial strategic significance.

For the Ukrainian government, the recapture of Crimea and the naval base of Sevastopol would not only mark Ukraine’s total defeat of Russian aggression, but would also eliminate Russia’s ability to blockade Ukraine’s Black Sea ports, and make any future Russian invasion of Ukraine much more difficult.