Korea–United States relations began formally in the late 1880s, but in these early years were modest. Washington was largely a bystander as Korea was embroiled in the competition between China, Japan, and Russia. Korea hoped that relations with the United States might help protect it from this regional struggle for power. In the end, Korea was just not that important to the United States. After World War II, Korea reemerged from Japanese occupation but was soon divided by Washington and Moscow. As the Cold War played out, the country remained separated into two hostile regimes. North Korea attempted to reunite the peninsula by force and nearly succeeded. However, after three years of war, the fighting ended with an armistice, locking in the divisions of North and South. After the war, the United States and South Korea signed the Mutual Defense Treaty and established a formal alliance that has lasted for over six decades. This chapter describes the early history of the relationship between the two countries.