WASHINGTON — A top commander of U.S. forces in Afghanistan says he needs thousands of additional troops to combat violence along the Pakistani border, a requirement that appears to be at odds with recommendations from Army Gen. David H. Petraeus on future troop levels in Iraq.

Because of strains on the military, plans to boost the number of troops in Afghanistan depend on reducing the force in Iraq. Petraeus' plan, which President Bush is expected to approve in an appearance at the National Defense University tomorrow, would slow the reduction of combat troops in Iraq, freeing up only one full Army combat brigade in Iraq for redeployment to Afghanistan. That redeployment would not happen until early next year.

In addition to the combat brigade of about 3,500 to 4,000 troops, U.S. officials also plan to withdraw about 2,000 noncombat support personnel from Iraq and shift about 1,300 Marines from Iraq's Anbar province to western Afghanistan.

Some within the Pentagon had been pushing for a faster and larger reduction of combat forces from Iraq and a more aggressive buildup in Afghanistan. They preferred withdrawing as many as three combat brigades so that additional forces could be sent to Afghanistan before the end of the year.

Pressure from U.S. commanders in Afghanistan for more troops has become the central point in a public debate among senior U.S. military officers and a source of tension among Pentagon planners, who are at odds over how quickly to shift forces from an increasingly stable Iraq to an increasingly violent Afghanistan.

Army Maj. Gen. Jeffrey J. Schloesser, who took command of American-controlled eastern Afghanistan in April, said Friday that coalition forces are at no risk of losing in Afghanistan without additional brigades. But he said that continuing with the present level of about 34,000 U.S. troops for an extended period would lead to only a "slow win."

"It's not the way that I think the Afghans, the international community and the American people would like to see us conduct this war," Schloesser said in a video conference with reporters at the Pentagon. "It will take longer, the way we are doing it right now. ... I'd like to speed that up."

Petraeus, reluctant to risk hard-won security gains in Iraq, had wanted to keep troop levels in Iraq at 15 brigades through next June, according to a Pentagon official who described the internal deliberations on condition of anonymity. But under a compromise with the Joint Chiefs of Staff, the first brigade to shift from Iraq to Afghanistan — the 3rd Brigade of the 10th Mountain Division — will deploy in February.

U.S. officials say that insurgents and extremist groups use Pakistan's tribal areas as a base to attack foreign forces across the border in eastern Afghanistan. U.S. commandos conducted a raid into Pakistan earlier this week, angering the government, and the United States targets Islamic militants there with airstrikes by unmanned Predator drones.

Schloesser said that recent Pakistani military action in that country's lawless tribal regions have begun to stem some of the bloodshed associated with cross-border attacks by militants. Still, violence overall in eastern Afghanistan is up 20 percent to 30 percent in the first eight months of the year compared to last year, he said.

In July, nine Americans were killed in a coordinated insurgent assault on an isolated outpost in northeastern Afghanistan.

U.S. commanders in eastern Afghanistan have "very low numbers of troops," Schloesser said. That allows them to attack enemy positions, but not hold captured territory and begin the rebuilding necessary to win in a counterinsurgency effort.