At the end of the previous century, U.S. policy was starting to shift to a more global or imperial perspective. What was once a policy of isolationism had changed rapidly into one of imperialism. In the beginning of the 1900's, America began to amass a military fleet to control the ever-expanding territories controlled by the U.S. Government policies actively increased control over Central and South American countries. For example, a plot developed in Panama against the established government to ensure the building of the Panama Canal, deemed vital at the time to U.S, trade interests.
In 1917 and in the context of World War I, President Wilson declares war, meaning the U.S. will now participate in the war with the allies and initiates the idea of protecting democracy at any cost, in any place.
World War II greatly expanded America's ability to participate and influence politics on a global scale. With military action on almost every continent, the US expanded its interests, both politically and economically.
In essence, a number of burgeoning economic issues that existed and were seen as a benefit to the once isolationist republic, helped the United States transition to a more interventionist and aggressive competitor for resources on the global stage.
