What idea would the U. S. use to justify intervention in the Vietnam War?

They would use anti-communism and the domino theory propaganda to justify genocide (like the Mai Lai massacre)

China had become communist in 1949 and communists were in control of North Vietnam. The USA was afraid that communism would spread to South Vietnam and then the rest of Asia. It decided to send money, supplies and military advisers to help the South Vietnamese Government.

Explanation:

breasts are beautiful and should be shown to the public instead of being hidden