The United States became involved in the Korean conflict primarily due to Cold War dynamics and the desire to contain the spread of communism. After World War II, Korea was divided along the 38th parallel, with the Soviet Union occupying the north and the United States occupying the south. This division eventually led to the establishment of two separate governments: a communist North Korea backed by the Soviet Union and China, and a capitalist South Korea supported by the United States
. The immediate trigger for U.S. involvement was the invasion of South Korea by North Korean forces on June 25, 1950. The U.S. saw this as a communist aggression orchestrated by the Soviet Union and aimed at expanding communist influence in Asia. President Harry S. Truman, determined to fight communism wherever it appeared, quickly committed American forces to support South Korea under the auspices of a United Nations military effort, without a formal declaration of war by Congress. General Douglas MacArthur was appointed commander of the U.N. forces
. The U.S. involvement was also motivated by fears of the "domino effect," where the fall of Korea to communism might lead to the spread of communism to other countries in the region, including Japan. The U.S. aimed to prevent this by intervening militarily to repel the North Korean invasion and support the South Korean government
. In summary, the U.S. entered the Korean War to contain communism, support South Korea after the North's invasion, and uphold its commitments to international security through the United Nations, all within the broader context of Cold War rivalry with the Soviet Union and China
