How will the war in Ukraine shape international politics? In principle there are two ways to address this question. The first is simply to extrapolate into the future any actions or reactions that we can observe today. The second, which is explored below, is to organize our thinking theoretically, to ask what may turn out to be the long-term effects of the major causes set in motion by the war. I organize the discussion in terms of a theory of international politics—realism, mainly structural realism. Russia’s invasion of Ukraine serves as another reminder that war remains an ever-present danger in an international system that is anarchic—ie, devoid of any central authority with the wherewithal to protect states from aggression. States must therefore prepare to defend themselves. In the heady aftermath of the liberal West’s victory over the Soviet empire, and the apparent triumph of the US-led, liberal world order, many instead believed that interstate war would become a thing of the past. States now face strong incentives to reembrace tried and tested tools of self-preservation developed in earlier times.

Full story by Barry Posen is available here: https://www.defensepriorities.org/explainers/hypotheses-on-the-implications-of-the-ukraine-russia-war