"When the first big American fighting units began arriving in South Vietnam in 1965, there was a standard explanation for the United States presence. "We've come here to stop the spread of Communism," the soldiers would say without hesitation. "If we don't stop them here we may be fighting them in San Francisco next." Sometimes the soldiers also mentioned giving the South Vietnamese the opportunity to live under a democratic system." Download New York Times article from "On This Day", in PDF format.