There is perhaps no greater danger to the success of American efforts in Iraq than the prospect of a congressionally mandated timeline for withdrawal. Depriving commanders on the ground of the ability to make decisions about required force levels dramatically increases the likelihood of losing our recent hard-fought gains. And congressional attempts to legislate a timeline based on the military command's current estimates of its ability responsibly to reduce American forces in Iraq will restrict our ability to respond to unforeseen developments in a complex and rapidly changing situation.

Various members of Congress want to wind down the U.S. military commitment in Iraq. Some are starting to discuss "nonbinding" timelines that express Congress's desire for the military command to reach force-level targets by certain times. Some want to restrict the mission of the remaining troops to counterterrorism and support activities--a return to the reactive posture of 2006, when sectarian violence in Iraq spiked to record levels. All of this would be a huge mistake.

Generals David Petraeus and Raymond Odierno, the U.S. commanders in Iraq, oppose any legislated timeline for drawing down U.S. forces. On September 7, the New York Times reported that "even in internal administration deliberations [Petraeus] had described conditions that must be met before a reduction." General Odierno has said repeatedly that any drawdown of American forces must be deliberate, gradual, and based on conditions on the ground. The generals' emphasis on a "conditions-based" drawdown is far from rhetoric. Rather, their support of a "conditions-based" drawdown reflects the sophisticated military concepts underlying the counterinsurgency strategy.

Petraeus, Odierno, and their division commanders have spoken repeatedly of three basic phases in a counterinsurgency: clearing the enemy from safe havens; controlling neighborhoods (assuring that U.S. and Iraqi forces can move through them, but the enemy cannot); and retaining these neighborhoods with Iraqi Security Forces.

"This new plan involves three basic parts: clear, control, and retain," explained General Joseph Fil, commander of Coalition forces in Baghdad, on February 16, 2007. "The first objective within each of the security districts in the Iraqi capital is to clear out extremist elements neighborhood by neighborhood in an effort to protect the population. And after an area is cleared, we're moving to what we call the control operation. Together with our Iraqi counterparts, we'll maintain a full-time presence on the streets, and we'll do this by building and maintaining joint security stations throughout the city."

General Odierno, the commander of Multi-National Corps-Iraq, has already demonstrated the value of deploying units properly to set conditions for successful operations. As new forces arrived in Iraq during the first half of this year, Odierno carefully prepared for "the battle for the belts," the areas around Baghdad where al Qaeda had its safe havens. He deployed two of the new brigades to Baghdad and three to the belts around the city. He divided brigades so that each area had the optimal combination of battalions--light and heavy infantry, cavalry, and artillery. During this deployment, General Odierno began preliminary operations to encircle Baghdad and to establish U.S. forces within the city. He launched a Baghdad-wide offensive, Operation Enforcing the Law, to set the preconditions for clearing enemy sanctuaries there.