Iraq will only be another Vietnam if the home front collapses, as it did following the Tet offensive, which began on the eve of the Chinese New Year, Jan. 31, 1968. The surprise attack was designed to overwhelm some 70 cities and towns, and 30 other strategic objectives simultaneously. By breaking a previously agreed truce for Tet festivities, master strategist Gen. Vo Nguyen Giap in Hanoi calculated that South Vietnamese troops would be caught with defenses down.

After the first few hours of panic, the South Vietnamese troops reacted fiercely. They did the bulk of the fighting and took some 6,000 casualties. Vietcong units not only did not reach a single one of their objectives -- except when they arrived by taxi at the U.S. Embassy in Saigon, blew their way through the wall into the compound and guns blazing made it into the lobby before they were wiped out by U.S. Marines -- but they lost some 50,000 killed and at least that many wounded. Giap had thrown some 70,000 troops into a strategic gamble that was also designed to overwhelm 13 of the 16 provincial capitals and trigger a popular uprising. But Tet was an unmitigated military disaster for Hanoi and its Vietcong troops in South Vietnam. Yet that was not the way it was reported in U.S. and other media around the world. It was television's first war. And some 50 million Americans at home saw the carnage of dead bodies in the rubble, and dazed Americans running around.

As the late veteran war reporter Peter Braestrup documented in "Big Story" -- a massive, two-volume study of how Tet was covered by American reporters -- the Vietcong offensive was depicted as a military disaster for the United States. By the time the facts emerged a week or two later from RAND Corp. interrogations of prisoners and defectors, the damage had been done. Conventional media wisdom had been set in concrete. Public opinion perceptions in the United States changed accordingly.

RAND made copies of these POW interrogations available. But few reporters seemed interested. In fact, the room where they were on display was almost always empty. Many Vietnamese civilians who were fence sitters or leaning toward the Vietcong, especially in the region around Hue City, joined government ranks after they witnessed Vietcong atrocities. Several mass graves were found with some 4,000 unarmed civil servants and other civilians, stabbed or with skulls smashed by clubs. The number of communist defectors, known as "chieu hoi," increased fourfold. And the "popular uprising" anticipated by Giap, failed to materialize. The Tet offensive also neutralized much of the clandestine communist infrastructure.

As South Vietnamese troops fought Vietcong remnants in Cholon, the predominantly Chinese twin city of Saigon, reporters, sipping drinks in the rooftop bar of the Caravelle Hotel, watched the fireworks 2 miles away. America's most trusted newsman, CBS' Walter Cronkite, appeared for a standup piece with distant fires as a backdrop. Donning helmet, Cronkite declared the war lost. It was this now famous television news piece that persuaded President Johnson six weeks later, on March 31, not to run. His ratings had plummeted from 80 percent when he assumed the presidency upon Kennedy's death to 30 percent after Tet. His handling of the war dropped to 20 percent, his credibility shot to pieces.

Until Tet, a majority of Americans agreed with Presidents Kennedy and Johnson that failure was not an option. It was Kennedy who changed the status of U.S. military personnel from advisers to South Vietnamese troops to full-fledged fighting men. By the time of Kennedy's assassination in Nov. 22, 1963, 16,500 U.S. troops had been committed to the war. Johnson escalated all the way to 542,000. But defeat became an option when Johnson decided the war was unwinnable and that he would lose his bid for the presidency in November 1968. Hanoi thus turned military defeat into a priceless geopolitical victory.

With the Vietcong wiped out in the Tet offensive, North Vietnamese regulars moved south down the Ho Chi Minh trails through Laos and Cambodia to continue the war. Even Giap admitted in his memoirs that news media reporting of the war and the anti-war 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.

Hanoi's Easter offensive in March 1972 was another disaster for the communists. Some 70,000 North Vietnamese troops were wiped out -- by the South Vietnamese who did all the fighting. The last American soldier left Vietnam in March 1973. And the chances of the South Vietnamese army being able to hack it on its own were reasonably good. With one proviso: Continued U.S. military assistance with weapons and hardware, including helicopters. But Congress balked, first by cutting off military assistance to Cambodia, which enabled Pol Pot's Khmer Rouge communists to take over, which, in turn, was followed by a similar Congressional rug pulling from under the South Vietnamese, that led to rapid collapse of morale in Saigon.

The unraveling, with Congress pulling the string, was so rapid that even Giap was caught by surprise. As he recounts in his memoirs, Hanoi had to improvise a general offensive -- and then rolled into Saigon two years before they had reckoned it might become possible.

That is the real lesson for the U.S. commitment to Iraq. Whatever one thought about the advisability of Operation Iraqi Freedom, the United States is there with 100,000 troops and a solid commitment to endow Iraq with a democratic system of government. While failure is not an option for Bush, it clearly is for Sen. Edward Kennedy, D-Mass., who called Iraq the president's Vietnam. It is, of course, no such animal. But it could become so if Congressional resolve dissolves.

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 the anti-war movement in the United States, which led to the collapse of political will in Washington, was "essential to our strategy."

Visits to Hanoi by Jane Fonda and former Attorney General Ramsey Clark and various church ministers "gave us confidence that we should hold on in the face of battlefield reverses."

America lost the war, concluded Bui Tin, "because of its democracy. Through dissent and protest it lost the ability to mobilize a will to win." Kennedy should remember that Vietnam was the war of his brother who saw the conflict in the larger framework of the Cold War and Nikita Khrushchev's threats against West Berlin. It would behoove Kennedy to see Iraq in the larger context of the struggle to bring democracy, not only to Iraq, but the entire Middle East.