Iraq is not Vietnam. There is no popular, anti-colonial insurgency in Iraq. Our opponents, who number only in the thousands in a country of 23 million, are despised by the vast majority of Iraqis. The Iraqi insurgents do not enjoy the kind of sanctuary North Vietnam, Cambodia and Laos provided. They do not have a superpower patron. These murderers cannot carry the banner of Iraqi nationalism, as Ho Chi Minh did in Vietnam for decades.

But if we are to avoid a debate over who "lost" Iraq, as we debated who lost Vietnam a generation ago, we must act urgently to transform our early military success into lasting political victory.

We lost in Vietnam because we lost the will to fight, because we did not understand the nature of the war we were fighting and because we limited the tools at our disposal.

The United States will fail in Iraq if our adversaries believe they can outlast us. If our troop deployment schedules are more important than our staying power, we embolden our enemies and make it harder for our friends to take risks on our behalf. When the United States announces a schedule for training and deploying Iraqi security officers, then announces the acceleration of that schedule, then accelerates it again, it sends a signal of desperation, not certitude.

Politics at home has handicapped our progress. Today some Democrats who supported the war in Iraq oppose spending the money required to win the peace. Others blindly criticize the administration without proposing an alternative policy that preserves U.S. interests.

With the exception of Joe Lieberman and Dick Gephardt, who are committed to victory in Iraq, it is unclear what the other Democratic presidential candidates would do differently to ensure an American victory -- or how they would handle the consequences of the early American withdrawal some advocate. Howard Dean has expressed ambiguity about the justness of our cause in Iraq. I hope he will learn that partisan anger is no substitute for moral clarity.

Administration officials must be careful not to adjust our military posture in Iraq for political reasons. The only legitimate reason to adjust our posture is to improve our ability to accomplish our mission or respond to our successes in stabilizing and rebuilding Iraq.

Prematurely placing the burden of security on Iraqis is not the answer. It is irresponsible to suggest that it is up to Iraqis to win this war. In doing so, we shirk the responsibility that we willingly incurred when we assumed the burden of liberating and transforming their country, for their sake and our own. If the U.S. military, the world's best fighting force, cannot defeat the Iraqi insurgents, how do we expect Iraqi militiamen with only weeks of training to do any better?

President Bush speaks frequently of the need to take the offensive in the war on terror, but in Iraq we too often appear to be playing defense. The truth is that we do not have sufficient forces in Iraq to meet our military objectives. In early September, the U.S. commanding officer in Iraq, Gen. Ricardo Sanchez, admitted that his forces could not handle any new eruption of conflict in Iraq. "If a militia or an internal conflict of some nature were to erupt," he said, ". . . that would be a challenge out there that I do not have sufficient forces for."

Since then, attacks on American forces have doubled, to more than 30 a day, and their increasing sophistication has made them more lethal.

Yet the number of American forces in Iraq has not increased. Our overall troop level in Iraq does not reflect a careful assessment of what it takes to achieve victory. It reflects the number of American forces who were in Iraq when the war ended -- minus the Marines who were sent home. Simply put, there does not appear to be a strategy behind our current force levels in Iraq other than to preserve the illusion that we have sufficient forces in place to meet our objectives.

I believe we must deploy at least another full division, giving us the necessary manpower to conduct a focused counterinsurgency campaign across the Sunni Triangle that seals off enemy operating areas, conducts search-and-destroy missions and holds territory.

While Iraqification will not solve our immediate security problems, we must move more quickly to transfer meaningful political authority to Iraqi leaders. The Coalition Provisional Authority continues to make a fundamental mistake in the way it interacts with the Iraqi people. The authority seems to think that all wisdom is made in America and that the Iraqi people were defeated, not liberated. For all the comparisons of postwar Iraq to Germany and Japan in 1945, the examples of Italy and France, liberated countries whose people were largely on our side, may be more instructive. The United States is treated as an occupying force in Iraq partly because we are not treating Iraqis as a liberated people.

It is our responsibility to help create the security in which Iraqi politics can flourish. We can leave it to the Iraqis to decide what kind of tax code they should have.

Iraq's transformation into a progressive Arab state could set the region that produced Saddam Hussein, the Taliban and al Qaeda on a new course in which democratic expression and economic prosperity, rather than a radicalizing mix of humiliation, poverty and repression, create a new modernity in the Muslim world that does not define itself in ways that threaten its people or other nations.

Failure to make the necessary political commitment to secure and build the new Iraq could endanger American leadership in the world, put American security at risk, empower our enemies and condemn Iraqis to renewed tyranny. It would be the most serious American defeat on the global stage since Vietnam.

The writer is a Republican senator from Arizona. This column was adapted from a speech he delivered to the Council on Foreign Relations.