Describe the united states' movement from isolationism to expansion-mindedness in the final decades of the nineteenth century. what ideas and philosophies underpinned this transformation?

The world wars. Mainly World War II when the United States earned the name the arsenal of democracy. At that time, Americans were beginning to believe that the world NEEDED the USA and that democracy had to spread throughout the globe. This led to the Korean and Vietnam War because American citizens felt obligated to be involved, at least in the beginning.

The answer should be europe