The Monroe Doctrine, established in 1823, was a pivotal policy in American foreign relations, asserting that any European intervention in the Americas would be viewed as an act of aggression requiring U.S. intervention. This doctrine was intended to prevent further colonization and interference by European nations in the Western Hemisphere, promoting American influence and fostering a sense of regional autonomy. It solidified the United States' role as a protector of newly independent nations in Latin America, ultimately laying the groundwork for future U.S. foreign policy in the region, as well as reflecting a growing sense of national identity and purpose.