1. The Spanish American War (1898) - The Spanish American war signaled America's rise and the relative decline of the European powers. The war also led to America aquiring territories and colonies in the Caribbean Sea and Pacific Ocean (the Philippines, Cuba, Puerto Rico, The Marianas and a host of other territories). The acquisition of the Philippines in particular led to permanent American involvement in Asian affairs.
2. The Building of the Panama Canal (1903) - The construction and completion of the Panama Canal has a number of important foreign policy implications. First it led to the United States' supporting secessionist factions, who separated the republic of Panama from Colombia, and it also led to the granting of sovereign land rights to the United States over the Panama Canal Zone. The Panama Canal had massive implications for the exercise of American foreign policy and military might; it greatly shortened the sea travel distance for both commercial and military vessels from the East to West coast, therefore making it easier for the U.S to exercise its influence in the pacific rim.
3. Intervention in China (Boxer Rebellion) - The intervention in China to suppress the Boxer rebellion was an important aspect in U.S foreign policy as it showed America's willingness to intervene militarily and to use force to secure its influence and interests. It also was one of the earlier examples of broad coalition building as the U.S intervened as part of an alliance of nations.
