As this issue goes to press, the war in Ukraine is far from over. It seems likely to go on for weeks or months or even years, whether as a grinding back-and-forth conflict, an insurgency fighting to overturn an occupation, or a global cataclysm. Yet since the moment the first missiles were fired, it has been clear that the invasion marked the start of a new era—one that will be defined not just by the outcome on the ground in Ukraine but also by the global response. In their resistance to the Russian assault, Ukrainians have powerfully demonstrated what’s at stake for them. The rest of the world is still grappling with what’s at stake for it.

For Americans, argues Robert Kagan, the war serves as a stark reminder “that they are part of a never- ending power struggle, whether they wish to be or not”—and “that there really are worse things than U.S. hegemony.” For the international order, writes Tanisha Fazal, the war threatens the principle that has underpinned stability for decades: “The norm against territorial conquest has been tested in the most threatening and vivid way since the end of World War II.” And for Western policymakers, contends Stacie Goddard, the war underscores the value of “institutional realpolitik”—a strategy that, rather than scrapping the existing international system, would deploy it to contain the coordinated yet distinct revisionist challenges mounted by China and Russia.

For Vladimir Putin, the war reflects what Daniel Treisman describes as “an emerging pattern—one that features anti-Western nationalism; angry, self-justifying speeches; and increasingly open uses of force,” first at home and then abroad. And for Ukrainians, the war represents an assault on, among much else, their history, with Putin, as Anna Reid explains, “resorting to military force and totalitarian censorship in a vain attempt to make reality closer to the myth.”

For all of us, meanwhile, the war has forced a fresh confrontation with risks and threats once dismissed as relics. It turns out, as Stephen Kotkin puts it in his sweeping analysis of geopolitics past and present, that “the West’s relatively brief respite from great-power competition with Russia constituted a historical blink of an eye.”

—Daniel Kurtz-Phelan, Editor

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