Final answer:
U.S. foreign policy during the early 1900s affected foreign relations by shifting from isolationism to imperialism, acquiring territories through the Spanish-American War, and implementing the Open Door Policy towards China.
Step-by-step explanation:
During the early 1900s, U.S. foreign policy had a significant impact on foreign relations. It marked a turning point in American foreign policy when the country shifted from isolationism to imperialism, seeking to extend its political, economic, and military control over other nations. This expansionist policy influenced relationships with countries in Africa, Asia, and the Pacific.
One example of U.S. foreign policy during this period is the Spanish-American War in 1898, which resulted in the U.S. acquiring territories such as Puerto Rico, Guam, and the Philippines. This acquisition of colonies expanded the United States' influence and led to interactions and conflicts with other nations.
Additionally, the U.S. implemented the Open Door Policy towards China, which called for equal trading rights and access to Chinese markets for all countries. This policy aimed to protect U.S. economic interests and prevent other powers from monopolizing trade with China.