What was the doctrine warning all European powers to discontinue colonization of Western Hemisphere?

The doctrine warning all European powers to discontinue colonization of the Western Hemisphere is known as the Monroe Doctrine, established in 1823 by U.S. President James Monroe. It asserted that any efforts by European nations to interfere in the affairs of the Americas would be viewed as acts of aggression, warranting U.S. intervention. The doctrine aimed to protect newly independent Latin American countries and prevent further European colonial expansion in the region.