Washington, D.C. ? The Army’s National Guard and Reserve are bracing for possible new and accelerated call-ups – spurred by high demand for U.S. troops in Iraq – that reserve leaders caution could undermine the citizen-soldier force as it struggles to rebuild.

Two Army National Guard combat brigades with about 7,000 troops have been identified recently in classified rotational plans for possible special deployment to Iraq, according to senior Army and Pentagon officials. One brigade could be diverted to Iraq next year from another assignment, and the other could be sent there in 2008, a year ahead of schedule.

Next year, the number of Army Guard soldiers providing security in Iraq will surge to more than 6,000 in about 50 companies, compared with 20 companies two years ago, guard officials said.

Senior Army leaders have made clear that without a bigger active-duty force, the only way they can maintain the intense pace of rotations in Iraq and Afghanistan is by relying more heavily on the reserves, which make up 52 percent of the Army’s total troops.