In the early hours of February 24, 2022, the Russian air force struck targets across Ukraine. At the same time, Moscow’s infantry and armor poured into the country from the north, east, and south. In the days that followed, the Russians attempted to encircle Kyiv. These were the first days and weeks of an invasion that could well have resulted in Ukraine’s defeat and subjugation by Russia. In retrospect, it seems almost miraculous that it did not. What happened on the battlefield is relatively well understood. What is less understood is the simultaneous intense diplomacy involving Moscow, Kyiv, and a...