Western defense ministers ended their conference at a U.S. air base in Germany on Friday afternoon still unable to persuade Germany to send its best battle tanks, the Leopard 2s, to Ukraine. The failure marked a rare and potentially damaging jolt to what has been a rapid flow of Western arms—and, still more unnerving, a solid show of Western unity—to help the Ukrainian army fight off the Russian invaders. The whole episode signals just how much Europe has changed in the 11 months since Vladimir Putin’s invasion—and also how much, in some ways, it hasn’t changed. Advertisement Even just a...