Military power has long underpinned the United States’ global hegemony, but the war in Iran is now putting that foundation to the test. What is unfolding is not just another conflict, but a potential turning point. Critics argue that Washington’s reliance on force over diplomacy and unilateral action over multilateral cooperation signals a shift toward coercion that may be accelerating the very decline it seeks to prevent. The question remains whether this moment reinforces U.S. primacy or marks a broader shift toward a more fragmented, post–United States world.