The Army has extended by two months the Iraq tours (search) of about 6,500 soldiers, citing a need for experienced troops through the Iraqi elections scheduled for late January.

About 3,500 soldiers of the 2nd Brigade, 1st Cavalry Division (search), and 3,000 from the 1st Infantry Division (search) headquarters will remain in Iraq two months longer than planned, Bryan Whitman, a Pentagon spokesman, said Saturday.

The purpose, Whitman said, is to "maintain continuity of forces in the theater during the election period."

Roughly 135,000 American troops are in Iraq.

Whitman said the extensions will result in a net addition of about 3,500 troops in the country, since replacements for the 3,000 from the 1st Infantry will delay their arrival until after the elections.

Soldiers of the 3rd Infantry Division, scheduled to replace the 2nd Brigade, 1st Cavalry, will not be delayed. Whitman said it was possible that the 3rd Infantry could accelerate its deployment if commanders in Iraq say that is necessary, but no decision has been made.

The Army had scheduled 10-month deployments for the units whose tours are being extended, rather than the usual 12-month tours, to stagger the rotation of forces in and out of Iraq this winter and avoid overburdening transportation systems.

A description of the troop extensions posted on the Pentagon's Web site Saturday mentioned "the troops' frustration" over having their tours extended. It said some of the soldiers previously had been told they would be leaving Iraq as early as November. Instead they will stay through January.

Army Gen. George Casey, the top U.S. commander in Iraq, requested the extensions in late September, and his immediate superior, Army Gen. John Abizaid, made the decision Oct. 16, the Pentagon said.

The decision appeared to mark the second time in recent weeks that soldiers of the 2nd Brigade, 1st Cavalry Division, have had their Iraq deployments extended. On Oct. 4 the U.S. military command in Baghdad announced that rather than complete its redeployment to Fort Hood, Texas, in December, the brigade was to begin heading home in January. It now appears they will stay through January.

"It makes sense to keep experienced soldiers who know the area and have developed relationships in Iraq on the ground during the election period," Whitman said. He stressed that the extensions will not exceed the Army's goal of keeping soldiers in Iraq no longer than 12 months.

Whitman said it was possible that other adjustments will be made to bolster U.S. and allied defenses in Iraq prior to the elections in January.

"The department will continue to be responsive to requests by the combatant commander for adjustments," Whitman said.

The 3,000 soldiers of the 1st Infantry Division headquarters, based in Wurzburg, Germany, will remain in Iraq for an extra 30 to 60 days. They previously were scheduled to have been replaced in January, before the elections, by the 42nd Infantry Division headquarters of the New York National Guard.

The 42nd Infantry will be the first division-level National Guard deployment into combat since World War II, reflecting the extraordinarily heavy reliance the Army is placing on part-time soldiers to provide troops for the Iraq mission. More than 40 percent of the U.S. force in Iraq is Guard or Reserve.

Whitman said it would be wrong to infer from the delayed deployment of the New York Guard unit that Pentagon officials doubt its readiness.