Almost 3 million Americans served in Vietnam. Between 1965 and 1973, the United States spent $120 billion on the war ($700 billion in 2007 dollars). This resulted in a large federal budget deficit. The war demonstrated that no power, not even a superpower, has unlimited strength and resources. But perhaps most significantly, the Vietnam War illustrated that political will, as much as material might, is a decisive factor in the outcome of conflicts.