How did President Harry Truman react to the North Korean invasion of South Korea?

President Truman asked Congress for a formal declaration of war.

President Truman decided to use atomic weapons against the enemy.

President Truman ordered General Douglas MacArthur to invade China.

President Truman ordered American troops moved from Japan to South Korea.

President Harry Truman reacted to the North Korean invasion of South Korea by ordering American troops to move from Japan to South Korea.

Explanation:

The invasion of South Korea by North Korea was when the real one to one conflicts between the United States and North Korea began. When North Korea invaded South Korea in 1950, the United States Army was still there in Japan. As soon as the news of the invasion of South Korea by North Korea surfaced, President Harry S. Truman ordered the US Army troops functional in Japan to move to South Korea and defend the invasion by North Korea.