Three years into the Sunni insurgency in Iraq, everyone from slicksleeved privates fighting for survival in Ramadi to the echelons above reality at the Pentagon still believes that eliminating insurgents will eliminate the insurgency. They are wrong.

There is a difference between killing insurgents and fighting an insurgency. In three years, the Sunni insurgency has grown from nothing into a force that threatens our national objective of establishing and maintaining a free, independent and united Iraq. During that time, we have fought insurgents with air strikes, artillery, the courage and tactical excellence of our forces, and new technology worth billions of dollars. We are further from our goal than we were when we started.

Counterinsurgency is about gaining control of the population, not killing or detaining enemy fighters. A properly planned counterinsurgency campaign moves the population, by stages, from reluctant acceptance of the counterinsurgent force to, ideally, full support.

American soldiers deride "winning hearts and minds" as the equivalent of sitting around a campfire singing "Kumbaya." But in fact it is a sophisticated, multifaceted, even ruthless struggle to wrest control of a population from cunning and often brutal foes. The counterinsurgent must be ready and able to kill insurgents — lots of them — but as a means, not an end.

Counterinsurgency is work better suited to a police force than a military one. Military forces — by tradition, organization, equipment and training — are best at killing people and breaking things. Police organizations, on the other hand, operate with minimum force. They know their job can't be done from miles away by technology. They are accustomed to face-to-face contact with their adversaries, and they know how to draw street-level information and support from the populace. The police don't threaten the governments they work under, because they don't have the firepower to stage coups.

The United States needs a professional police organization specifically for creating and keeping public order in cooperation with American or foreign troops during international peacekeeping operations. It must be able to help the military control indigenous populations in failing states like Haiti or during insurgencies like the one in Fallujah.

The force should include light armored cavalry and air cavalry paramilitary patrol units to deal with armed guerrillas, as well as linguistically trained and culturally attuned experts for developing and running informants. It should be skilled and professional at screening and debriefing detainees, and at conducting public information and psychological operations. It must be completely transportable by air and accustomed to working effectively with American and local military forces.

Bureaucratic ownership of this force will doubtless be controversial. Because the mission of international peacekeeping entails dealing mostly with civilians, the force would ideally be a civilian organization. But no civilian department is currently structured in a way that seems suitable.

At least initially, the force would most likely fall under the Department of Defense. The establishing legislation should include a firewall, however, to guard against the tendency of paramilitary units to evolve into pure warriors with berets, boots and bangles.

Crucial to the success of this force is that the American people thoroughly discuss and understand the organization and its mission.

The legislation establishing the police force should firmly anchor it in respect for human rights. Its mission will be to advance American ideals of justice and freedom under the law, and it must do so by example as well as word. That will be both difficult and critical in a place like Iraq, where it would have to wrest control of the population from insurgents who regard beheading hostages with chain saws as acceptable.

Stringent population control measures like curfews, random searches, mandatory presentation of identity documents, searches of businesses and residences without warrants, and preventive detention would be standard operating procedure. For such measures to be acceptable to the public, they must be based on solid legal ground and enforced fairly, transparently and impartially.

The police are used to functioning within legal restraints. Our armed forces, however, are used to obeying only the laws of war and the U.S. Uniform Code of Military Justice. Soldiers and Marines are trained to respond to force with massive force. To expect them to switch overnight to using force only as permitted by a foreign legal code, enforced and reviewed by foreign magistrates and judges, is quite unrealistic. It could also threaten their survival the next time they have to fight a conventional enemy.

Forcing the round peg of our military, which has no equal in speed, firepower, maneuver and shock action, into the square hole of international law enforcement and population control isn't working. We need a peacekeeping force to complement our war-fighters, and we need to start building it now.

Terence J. Daly is a retired military intelligence officer and counterinsurgency specialist who served in Vietnam as a province-level adviser. He wrote this commentary for The New York Times.