Europe, as the German philosopher Peter Sloterdijk recently wrote, has ended a long “vacation from history.” We have crossed the threshold into a gloomier era that is once again characterized by power flexing and great-power politics. The United States’ claim to global leadership is being challenged, perhaps even squandered. And the international order that was based on rights and rules, imperfect as it was even in its best days, no longer exists. Russia’s violent revisionism in its brutal war