The main countries involved in the Vietnam war were North and South Vietnam. North Vietnam was backed up by the communist Allies which were the People’s Republic of China, Soviet Union, Pathet Lao, Khmer Rouge and North Korea. South Vietnam was backed up by the anti-communist countries and members of the South East Asia Treaty Organization. Those countries were the United States, South Korea, Australia, the Philippines, New Zealand, Thailand, Khmer Republic, Kingdom of Laos and Republic of China. There was 2 communist allies that would send men and material to support South and North Vietnam. There was at least 21 countries to be involved in the entire war in Vietnam. Its cause was the communist party’s attempt to take over the country and