Why did Truman react so strongly when North Korea attacked South Korea? He wanted to protect US troops stationed in South Korea. He wanted to prevent the advance of Communism. He was worried that the Chinese Communists were behind the attack. He saw an opportunity to increase US defense spending.
The main reason why Truman reacted so strongly when North Korea attacked South Korea was because "He wanted to prevent the advance of Communism" since the US was in the Cold War.
