Answer:
The answer to the question: Why did President Harry Truman react so strongly when North Korea attacked South Korea, is: 1. He said he was enacting a resolution by the United Nations that sought to stop hostilities from escalating in the Korean Peninsula, and 2. He wanted to stop the malicious spread of Communism.
Step-by-step explanation:
In the 1950´s, when North Korea initiated attempts to invade South Korea, the United States, under the leadership of President Truman, decided not only to denounce what was happening, but more than that, to step in militarily. As such, on June 27th, 1950, Truman ordered U.S naval and air forces towards South Korea to help in stopping the advancement from North Korea, and the 7th Fleet to Taiwan, to prevent any possible moves by Communist China. The justification that Truman gave for this escalation in involvement was that he had to enforce a U.N resolution on stopping the escalating conflict, and the second was, that he wanted to stop the spread of Communism along Asia.