From an article by Mark Silverberg:
"In the end, American support for the Vietnam War faded. Giap admitted in his memoirs that news media reporting of the war and the antiwar demonstrations that ensued in America surprised him. Instead of negotiating what he called a "conditional surrender," Giap said they would now go the limit because America's resolve was weakening and the possibility of complete victory was within Hanoi's grasp.
Bui Tin, who served on the general staff of the North Vietnamese army, received South Vietnam's unconditional surrender on April 30, 1975. In an interview with the Wall Street Journal after his retirement, he made clear that the antiwar movement in the United States (which led to the collapse of political will in Washington) was "essential to our strategy."
These lessons have not been lost to a new era of Islamic fascists for we can see the implications arising, once again, in Iraq. America can win the war in Iraq. The question is whether we will lose the war here at home as we did during Vietnam. The terrorist opponents of a new Iraq are cleverly playing to American fears of another Vietnam and our media and some of our elected representatives are unwittingly buying into the strategy."
http://www.jfednepa.org/mark%20silverberg/measure_nation.html