The Monroe Doctrine was a foreign policy statement made by U.S. President James Monroe in 1823. It declared that the United States would not interfere with the affairs of European nations and, in return, European powers should not interfere with the affairs of the Americas. Monroe stated that the Western Hemisphere was no longer open to colonization or intervention by European nations, and that the United States would view any attempt by a European power to establish new colonies or interfere with the existing political order in the Americas as a hostile act. In effect, the Monroe Doctrine established the principle of American exceptionalism and marked the beginning of the United States' role as a global power.