In the next five months, most of the current 130,000 American troops in Iraq will be replaced with a smaller force of 105,000. Moreover, the new force will be 40 percent reservists (including National Guard), compared to 20 percent of the current force. The smaller US force, and lower proportion of active duty troops is part of the plan to turn most of the security work over to Iraqi forces. Iraqis need jobs, most Iraqi men have military training and the vast majority don't want Saddam or the Sunni Arabs back in charge. So US forces will provide back up for Iraqis as the civil war between the Sunni Arabs and the majority Shia and Kurds plays out.
US forces are suffering 40-50 permanent casualties (with victims leaving Iraq) a day. Most of these are due to disease and accidents, and only one or two troops a day are killed. A similar number of disease, accident and combat injuries are suffered, but these troops are treated and returned to duty without leaving the region.