what cause the viet cong?

Imperialistic forces invading their country and telling them what they can and can't do with their own government.

Yvette, your questions about the Viet Cong are sort of vague. I’m not sure what you are asking in either case. Do you mean, “who were the Viet Cong? Where did they come from?”

In 1954 France withdrew from its colony of Indochina after a war with a group of Communists named the Viet Mihn. The colony was broken up into four parts, North Vietnam, South Vietnam, Laos, and Cambodia. The Viet Mihn took control in N. Vietnam, anti-Communists forces took control in S. Vietnam, and neutral kings took control in Laos and Cambodia. According to the agreement to withdraw from Indochina there was suppose to be elections in North and South Vietnam in 1956 to unit the countries.

However the Prime Minister of S. Vietnam, Ngo Dinh Diem, took control, got himself elected president of S. Vietnam in rigged elections, and refused to allow the countrywide elections to take place. Unable to get themselves elected leaders in S. Vietnam, the leaders of N. Vietnam started arming South Vietnamese soldiers that had fled North after the country was partitioned, and infiltrating them back into South Vietnam to fight an insurgency against the S. Vietnamese government. Diem called these guerrilla forces the “Viet Cong,” which was short for “Vietnamese Communists.” The name stuck, and for the rest of the war that is what these guerrilla forces were called.

France had occupied parts of what was called "Indo-China" before, during and after WWII. They were supposed to give up their colonial claims after WWII, Roosevelt pressured them to but they didn't. Ho chi Min asked the US for help and didn't get it directly. But much as we did in Afghanistan when the Soviets invaded by funding and equipping the Taliban, we funded the Viet Cong as an insurgency against the French. Ho Chi Min fought and established his capitol in the North and drew a line with the government in the South. Because he got arms from China and Russia, we turned against him, entered on the side of the South and turned our backs on the Viet Cong, who were not part of the North Vietnamese army but joined them as a second paramilitary force fighting against the US-backed South Vietnamese army from within South Viet Nam, while the North Vietnamese army pushed down from the North.

The Vietnam war.