What have we been confronting with the insurgency in Iraq over the past three years?

The makeup and nature of the insurgency has evolved from the invasion and the fall of Saddam Hussein to the present. This is natural in wartime. The insurgency has always been primarily a Sunni-sponsored resistance effort, with renegade Shi'a militias, foreign terrorists, and organized criminals adding to the violence. In the past three years, the insurgency has grown larger, more sophisticated and experienced, better organized, and more competent. Dexter Filkins's reporting in The New York Times and Ahmed Hashim's new book Insurgency and Counter-Insurgency in Iraq describe the enemies of the new Iraq with singular clarity and accuracy.

The insurgents are not wholly unified, which presents the coalition and the Iraqi government with both an advantage and a disadvantage. On the one hand, the insurgents don't have a common strategy or doctrine, and can't act in unison to concentrate their strikes. However, there is no high command or single leader for the government to attack and capture, or centralized strategy to defeat. So there is not one battle, but a hundred separate and disconnected battles to be fought -- what Dr. Conrad Crane of the Army War College calls a "mosaic war."

Because of the disaggregate quality of the insurgency, it's not possible for its components to destroy the Iraqi security forces and drive out the coalition military. But the insurgents could make the country essentially ungovernable, and deny the population the security and basic needs expected by them from their newly elected government. This could undermine and de-legitimize the democratic process, and set the conditions for return of a "strong-man" leader in Baghdad. If threatened by unrelenting bombings, assassinations, and kidnappings, the Iraqi people may opt for personal security over personal liberties.

Given your knowledge of past counterinsurgency wars, how does this one compare in terms of the challenges and complexity? What mistakes are we repeating? What is unique about the insurgency in Iraq?

Political issues are almost always complex, and insurgencies, which are fundamentally political struggles, reflect that characteristic. Since these conflicts are usually grounded in social, political and economic failings attributed to a sitting government, these factors are all part of what fuels the violence, and so must all be addressed to quell the violence.

The chief initial mistake repeated from our engagement in Vietnam was the failure to recognize the true nature of the war. The military theorist Carl von Clausewitz posits that the first and supreme act of judgment for the statesman and commander is to understand the kind of war on which he is embarking. For over a year after the toppling of Saddam's statue in Baghdad, the senior U.S. political and military leaders and their staffs inside Iraq failed to grasp that they faced a growing armed resistance. This misapprehension is described in detail in George Packer's eyewitness account The Assassin's Gate. Fortunately, the current coalition leadership in Iraq does comprehend the reality of the fight they're in, which didn't happen in Vietnam until too late in the war to reverse the outcome.

What makes the Iraqi insurgency somewhat unique is its continuing disorganization. Only now, after three years, are the insurgents coalescing and carrying out more cohesive and coordinated actions. Beyond resistance against the occupation troops and the new Iraqi security forces, there has been little to unify the estimated 60 to 100 major insurgent groups. The insurgent leaders have apparently not attempted to establish a shared strategic goal and political vision, because they likely know one could never be agreed to. Such a discourse would turn insurgents against each other and weaken their overall anti-government and anti-coalition effort. So, their tacit objective is not to expel the coalition forces and defeat the Iraqi army and police, but to make as much of Iraq as they can ungovernable.

This makes the current war unique because most counterinsurgency theory is based on examples of highly centralized political-military insurgencies. Mao Zedong's Chinese communists, the Irish Republican Army, the Viet Cong, the Peruvian Sendero Luminoso, to name a few, represent such insurrectionist movements with a single common doctrine, strategy, objective and often a supreme leader or directing council. The Iraqi insurgency does not fit this model.

A continuing error by some commanders is over-reliance on massive firepower, particularly aerial bombing, which has killed large numbers of innocent civilians. These killings drive family and community members into the insurgency, and create lifelong antagonisms toward the United States. Some units have been very restrained in their use of artillery and bombing, but others have not. This problem is exacerbated by "air power" proponents who advocate substituting bombs for coalition troops as they withdraw.

What would be the effect were the United States to withdraw from Iraq before the country is stabilized? Why don't you like the term "exit strategy"?

The disingenuous term "exit strategy" implies that it is more important to leave than it is to win. It provides a convenient political excuse to withdraw from a mission before it is completed, under the false rationale of the priority to quickly finish a job and leave, and not loiter needlessly. It also infers that the remaking of Iraq -- the reordering of society and government after 30 years of dictatorship -- can be completely accomplished in the next year or so, and then the Iraqis can be left on their own, assured of peace and prosperity, with no need of oversight.

There is no historical basis for an "exit strategy" providing any sort of policy success. Dr. Andrew Erdmann's New York Times essay After Withdrawal, Engagement proposes the most promising approach to achieve U.S. objectives in Iraq and the region. He calls for broader and more meaningful involvement by the U.S. government as time goes on, not a rapid "exit" of Americans and American influence. What is going on elsewhere in the world that is more important that ensuring our success in Iraq?

Based on past insurgencies, how long do you expect this one might take?

There is no way to predict the life expectancy of the Iraqi insurgency. There are simply too many variables that bear on the outcome of the fight. During the 20th century, the average duration of an insurgency -- and there have been over 50 of note -- has been about 10 years. Some insurgencies are striking in their brevity. The 1920 rebellion in Iraq was suppressed in less than a year. By contrast, the insurgency in Northern Ireland has been ongoing since 1968 -- that's 38 years. Colombia has been fighting the FARC rebels for over 40 years.

If the right steps are taken in Iraq, the current insurgency could be brought to heel and the levels of political violence contained in a few years. Some of the major steps must be: to create a functioning national government, which is not achieved just by holding elections; to revitalize the Iraqi economy, which goes beyond small-scale construction projects; and to constitute an effective police force and intelligence service. Along with these, the court system must assert itself to establish rule by law. This will collectively undermine the insurgents' influence in the population.

The next major issue will then be fighting the organized crime syndicates operating in collusion with the insurgents. These mafia-like criminal groups are taking advantage of the lawlessness and social chaos to loot, smuggle, steal, kidnap and murder-for-profit, among other illegal activities. Numerous incidents of criminal violence will almost certainly continue after a political settlement is reached.

Some warn of a scenario in which the insurgency wanes but sectarian violence escalates and leads to civil war in Iraq. What are your thoughts on this scenario? What could the U.S. military do? Would it even choose to intervene in a civil war?

Many analysts and observers believe that civil war is already underway in Iraq, kept in check by the presence of coalition military forces. It is another of the contradictions of insurgencies that as much as U.S. forces are disliked by most Iraqis, the senior Iraqi political leaders -- particularly among the Sunnis -- have quietly indicated their preference for the American troops to not leave immediately. They are the guarantors of the safety of the Sunnis from violent retaliation by revengeful Shi'as, and the force restraining non-governmental militias from fighting each other for political standing.

What do you think will be the legacy of this war on the U.S. military? It's been a sharp learning curve for them, true? How well prepared were they to take on such an opponent? How fast and well have they learned?

It's worth noting that the counterinsurgency most often cited as a model of success, the British-led fight against the communist insurgency in colonial Malaya after World War II, began with great difficulty. In the first three years of what became a 12-year war, serious errors were made, high-ranking leaders had to be replaced, and the communist movement grew in military and political power. Then the British started getting it right, and nine years and several elections later they were able to grant independence to the new, mostly peaceful and politically stable country of Malaysia. An excellent study of the Malaya and Vietnam conflicts and the U.S. military's institutional capacity to usefully assess its own experiences is John Nagl's Learning to Eat Soup with a Knife.

Three years into the battle for Iraq, the U.S. military has shown a remarkable adaptation to the demands of the conflict. Junior officers in particular, lieutenants and captains, have quickly comprehended the nature of the insurgency and its context and are very flexible, intellectually and organizationally, in carrying out their missions. There is an internal recognition in the armed forces that supporting U.S. global interests in the future will require the ability to do more than launch blitzkrieg-type forays to topple unpopular regimes. However, this view is not universally held, and debate on the subject is ongoing.

The legacy of the war in Iraq will hopefully be the end of the 20th century Cold War mentality and wishful thinking in the planning of military operations, and the rise of a new generation of veteran officers who understand how to wage war and win peace in the 21st century.

Do you think the United States has been held back in fully fighting this war due to insufficient forces on the ground, or Americans' aversion to taking high casualties, or the political controversy surrounding the origins of the war?

All these self-imposed restraints, and more, such as the exceeding use of marginally capable contractors and lack of rigorous fiscal auditing, have detracted from the prosecution of the counterinsurgency campaign by the United States government and its armed forces.

The central issue which has been the focus of analysts' criticisms has been a paucity of competent American civil and military leadership at the senior-most level in the period before and then after the invasion. The arrival of Gen. George Casey in Iraq was the beginning of the improvement of the American military effort, and the appointment of Ambassador Zalmay Khalilzad to the embassy in Baghdad markedly enhanced U.S. diplomatic engagement and activities with the emerging Iraqi government.

Vast resources and monies are committed to Iraq. The question is not one of limitations on forces and assets, but of their appropriate implementation and application. This is being resolved, although the financial wastage to this point has been staggering.

At this point in time, what are your thoughts on the most likely outcome?

I hope for the best, since both my sons will be serving in Al Anbar province by this spring. Travis is a Marine, and his twin brother Grant is an Army paratrooper.

I remain concerned but encouraged. We can't be defeated by the insurgents or their criminal and extremist allies. But we can fail to help build a new Iraq with viable economic, political and social institutions. Without these, civil war may consume the country, or a dictator may come to power, or Iran may intervene militarily. Looking back on each of my four tours of service in Iraq, from January 2004 to December 2005, I have seen distinct and steady improvement in the coalition and Iraqi counterinsurgency fight, from near-chaos to a disciplined, purposeful campaign. We may yet succeed. We certainly have the capacity; the question may ultimately be one of will.