The foundations of the post-1945 international order, long anchored by U.S. leadership, are shifting. Amid intensifying geopolitical rivalry, democratic backsliding, and strategic fatigue in Washington, the question arises: what if the United States no longer plays its pivotal role in international security? Simultaneously, the Global South is asserting new political and economic agency, complicating the old binaries of West vs. Rest. For Europe, this landscape is both a challenge and an inflection point.