I believe this is true but I'm not completely sure.
Social Contract
When we choose our politicians the idea that we elect them to protect our rights and freedoms in return for giving them power and losing some of ours is a social contract.
A; Indians would blend into white culture after the buffalo died out.
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.