A. The Spanish-American War Marks Transformation in US Foreign Policy
The Treaty of Paris left the United States of America of four colonies of Spanish Empire - Cuba,Puerto Rico,Guam, and Philippine Islands, under its power. Having such colonies under its control makes the United States of America a world power after demonstrating such prowess against the Spanish Forces. Also it left the United States a powerful country aside from the European countries who dominated the world affairs.
Giving Cuba it's independence and having the other islands as it's colony signals a new age of American expansion and role in the world balance. The war becomes an opportunity for the nation to prove itself capable of becoming a powerful country that can determine the faith of world.
C. President Wilson Attempts to Transform World Affairs
United States President Woodrow Wilson attempts to transform world affairs by creating the League of Nation and Treaty of Versailles after the First World War of The Great War. The League which is created to serve and maintain world order and peace was ineffective like on how it handles the Italian invasion in Ethiopia.
Also the Treaty of Versailles attempts to prevent another world war by demilitarizing Germany and it's capacity to wage war becomes the powder keg of rise of Nazi Germany under Adolf Hitler. Such events lead the world instead of another world war which is larger and more horrid than the first one.