The states newly formed from French Indochina (North Vietnam, South Vietnam, Cambodia and Laos) were prevented from taking part in any international military alliance as a result of the Geneva Agreements signed 20 July of the same year concluding the end of the First Indochina War.[17] However, with the lingering threat coming from communist North Vietnam and the possibility of the domino theory with Indochina turning into a communist frontier, SEATO got these countries under its protection – an act that would be considered to be one of the main justifications for the U.S. involvement in the Vietnam War.[18] Cambodia, however rejected the protection in 1956.[19]