Outrage has irrupted over President George Bush’s use of the Vietnam analogy in his recent speech to the Veterans of Foreign Wars to suggest the catastrophic consequences of premature US withdrawal from Iraq. "Invoking the tragedy of Vietnam to defend the failed policy in Iraq is as irresponsible as it is ignorant," decried Senator John Kerry. Senator Edward Kennedy opined that the US "lost the war in Vietnam because our troops were trapped in a distant country we did not understand, supporting a government that lacked sufficient legitimacy."

The initial use of the Vietnam analogy comes not from President Bush, but from al-Qaeda and other radical Islamist adversaries.

However, the initial use of the Vietnam analogy comes not from President Bush, but from al-Qaeda and other radical Islamist adversaries. They frequently invoke Vietnam as their model for Iraq. No one has yet accused them of being irresponsible or ignorant in drawing the following lessons from it. One, you can win a war against the United States without ever defeating it militarily. Two, it is not necessary to win the "hearts and minds" of the indigenous population, but to manipulate the "hearts and minds" of the American people. Three, you can degrade the political will of the US to the point that it will not only withdraw, but also abandon its allies to the mercies of their opponents. As Ayman al-Zawahiri, second in command to Osama bin Laden, wrote to the now late Abu Musab al-Zarqawi in Iraq in 2005: "the aftermath of the collapse of American power in Vietnam – and how they ran and left their agents – is noteworthy."

From reactions to Bush’s speech, it is clear many people still think that the US lost a guerrilla war in Vietnam. In order to understand Vietnam as a model for insurgents in Iraq, we need to recall exactly what happened there, just as they do. By 1972, the US had withdrawn all ground forces from South Vietnam in the process of "Vietnamisation." In the spring of that year, North Vietnam launched a World War Two-style invasion with some 23 divisions, including hundreds of Soviet T-54 tanks. South Vietnamese ground forces, backed by US air support and naval gunfire, stopped this offensive and was in the process of reversing it when Henry Kissinger agreed to a halt in place for negotiations. It took North Vietnam several years to recover from its losses of some 100,000 men (according to North Vietnamese General Tran Van Tra) and to rebuild itself into the then fifth largest military force in the world.

By 1975, when North Vietnam tried another massed armored invasion, several key things had changed. The Soviet Union had quintupled its aid to the North, while the United States had cut its aid to the South by two-thirds. Also, the 1973 Case-Church amendment had passed Congress, cutting off all funding for any further US military operations in Indochina. This rendered meaningless the US promise to come to South Vietnam’s aid if the North broke the 1973 Paris peace treaty.

When North Vietnam struck with a score of divisions in 1975, commanding General Van Tien Dung knew that US airpower would not come to the rescue and that the South would soon run out of ammunition and petrol, which it did. I will never forget my meeting in California with the former military mayor of Da Nang on the evening of the day that he learned he would never see his wife and several of his children again. He recounted the estimated ratio of incoming North Vietnamese fire as against what he was able to return because of the lack of supplies. It was nearly twenty to one against him. The North won because we abandoned the South.

Earlier this summer, Senator Joseph Biden, the chairman of the Senate Foreign Relations Committee warned on TV that failure in Iraq would have broad consequences. Unlike Vietnam, he said, "the other shoe would drop." In Vietnam, Senator Biden thinks that there was no other shoe to drop; it was an isolated loss. What he apparently does not understand is that Iraq is the other shoe dropping from Vietnam. We are living out our failure in Vietnam today in Iraq. The model of Vietnam is what incites the opponents of the US to believe that they can defeat us. In fact, al-Qaeda saw the Democratic win of Congress in the mid-term elections as proof of their progress. In a 2006 tape, Zawahiri announced to the Democrats, "The first is that you aren't the ones who won the mid-term elections, nor are the Republicans the ones who lost. Rather, the Mujahideen – the Muslim Ummah's vanguard in Afghanistan and Iraq – are the ones who won, and the American forces and their Crusader allies are the ones who lost."

Zawahiri’s "vanguard" is continuing its strategy of terror. The state of confusion into which we are thrown by what seem to be senseless acts of brutal violence in Iraq produce the very effects the terrorists intend: our incomprehension and demoralisation. We conclude that we don’t belong, as Senator Kennedy might say, "in a distant country that we don’t understand," and should therefore leave. Also, how can we continue to support an incompetent and corrupt Iraqi government that seems to lack "sufficient legitimacy"?

It may be too early to tell if the US is now pursuing the correct policy in Iraq. However, its enemies believe that they are and, given some of the responses to President Bush’s speech, they may well feel encouraged to think so. Perhaps the side that correctly understands the lessons of Vietnam will win.