American Empire is a term referring to the political, economic, military an cultural influence of the United States. The concept of an American Empire was first popularized in the aftermath of the Spanish-American War of 1898. The sources and proponents of this concept range from classical Marxist theorists of imperialism as a product of capitalism, to modern liberal theorists opposed to what they take to be aggressive U.S. policy, to neo-conservatives who believe the U.S. must embrace an imperial role.