Final answer:
The United States joined the Korean conflict to prevent the spread of communism, in line with its Cold War policy of containment. The U.S. took part in a United Nations Security Council response to North Korea's invasion of South Korea in 1950 with the goal of stopping the expansion of communism in Asia.
Step-by-step explanation:
Why the United States Joined the Korean Conflict
The question asks why the United States joined the conflict in Korea, leading to the separation of North and South Korea with different political ideologies. The correct answer is B. To prevent the spread of communism. Following World War II, Korea was divided at the 38th parallel, with the Soviet Union controlling the North and promoting communism, and the United States controlling the South and supporting capitalism. The political climate was very tense with each superpower wanting to curb the influence of the other's ideology.
In June 1950, North Korea, backed by the Soviet Union, invaded South Korea in an effort to unify the peninsula under communist rule. The United Nations Security Council, led by the United States, responded to this act of aggression and the U.S. involvement was principally aimed at containing the expansion of communism, a key component of U.S. foreign policy during the Cold War. The Soviet Union abstained from vetoing the UN's call for a military response, leading to the U.S.-led coalition entering the conflict. This occurred within the broader context of Cold War tensions, where the spread of communism was viewed as a direct threat to the capitalist world, prompting the U.S. to take action in Korea.
The conflict eventually led to the Korean Armistice Agreement in 1953, which created the Demilitarized Zone (DMZ) near the 38th parallel, effectively solidifying the division of Korea into two separate entities with opposing ideologies: the communist North and the capitalist South.