Why did cold war tensions rise in the years after the creation of North and South Vietnam.

Because it became a hot spot for confrontation between Communist USSR and Capitalistic US.

Tensions rose in North and South Vietnam during the Cold War because North Vietnam was a communist country while South Vietnam was a democratic and capitalist country. These two very different ideologies represented the essence of the Cold War, as the United States was pro-democratic and pro-capitalism while the Soviet Union was pro-communist. Both the US and Soviet Union would get involved in Vietnam, as a civil war between the two countries resulted in an all out international conflict. The US was trying to stop the spread of communism into South Vietnam while the Soviet's were trying to do the complete opposite.