Source: Petraeus submitted report on troop cuts

There currently are 15 combat brigades in Iraq and a total of 146,000 troops, including tens of thousands that perform support, rather than direct combat, functions.

U.S. and Iraqi officials are working on a security agreement that would include at least a notional timeline for phasing out U.S. forces, to include a pullback of combat troops from Iraqi cities by June 2009 and a broader withdrawal by the end of 2011. That is separate from Petraeus' recommendations to Gates, which are thought to be focused more on shorter-term reductions.

Petraeus, along with his soon-to-be-successor, Lt. Gen. Ray Odierno, and the No. 2 U.S. commander in Iraq, Lt. Gen. Lloyd Austin, has been doing what he calls "battlefield calculus" — studying ways of adjusting the positioning of U.S. troops in Iraq to possibly enable an overall reduction.

The commander of U.S. forces in western Iraq, for example, has said he could get by with fewer troops because security there has improved markedly and Iraq's army and police have gotten better. Security is more of an issue in areas north and northeast of Baghdad.

Based on that study, results of which have been provided by Petraeus to his superiors in Washington — and weighing a range of other factors such as trends in the level of violence — Petraeus has come up with "tentative recommendations" to Gates and others, the senior military officer said.

"However, the analysis is still ongoing and no decisions have yet been made," the officer said.