Why did cold war tensions rise in the years after the creation of north and south vietnam

This brought about the Vietnam War, which was the fight between North Vietnam and the alliance of South Vietnam and the United States. North Vietnam was being taken over and controlled by communism and was being supplied with Russian equipment such as AK-47's and other military supplies. the United States with the aid of a democratic backed South Vietnam tried to contain the spread of communism in the North. The war made tensions rise between the United States and Soviet Union. I hope this helps :)