Pax Americana, often identified with the "Long Peace", is a term applied to the concept of relative peace in the Western Hemisphere and later in the world after the end of World War II in 1945, when the United States became the world's foremost economic, cultural, and military power exercising primary responsibilities for world order. Though in large measure based on consent and cooperation, the defining feature of the Pax Americana is unipolarity, world organization around a single center of power. The structure and global reach of the Pax Americana have frequently drawn comparisons to the Roman Empire, with scholars and critics alike debating whether it constitutes a modern-day "New Rome" a framing that has garnered significant academic discourse on the nature of American imperialism, military overstretch, and decline.