Vietnam presumably taught us that the United States could not serve as the world's policeman; it should also have taught us the dangers of trying to be the world's midwife to democracy when the birth is scheduled to take place under conditions of guerrilla war.
We have war when at least one of the parties to a conflict wants something more than it wants peace.
I believe that detente was having almost the opposite effect of what was intended. What was intended was to sort of end the contest for power and to stop Soviet expansion, especially by military means and the military build-up, the military contest