The idea is among options being considered in response to a request in the last couple of weeks by Gen. David Petraeus, U.S. commander in Iraq, said the official who spoke on condition of anonymity because the idea has not been approved.

More than 7,000 Schofield Barracks soldiers who left Hawai'i in July and August are now past their seventh and eighth months of a deployment to northern Iraq.

Schofield officials said there has been no announcement of a combat extension beyond the 46 extra days that recently were added onto the year-long deployment for 1,000 soldiers with the 25th Special Troops Battalion, including the division headquarters and Tropic Lightning band.

Those soldiers will now be coming home sometime in September.

"At this point we haven't heard anything through any official channels (about additional extensions)," said Schofield spokesman Kendrick Washington. "We're aware that the Pentagon is looking at extending various brigades in Iraq, but at this point we haven't been told that any additional 25th (Infantry Division) soldiers are part of that."

Because Petraeus believes the troop increase President Bush announced in January has produced some momentum in fighting violence in Iraq, Petraeus wants to maintain troops at that level past the summer, the official said.

Defense officials are looking at the idea of a maximum 120-day extension for five active duty brigades that would otherwise come home in the coming months — four ground units and one aviation combat brigade totaling roughly 15,000 troops, the official said. The plan would have to be approved by Defense Secretary Robert Gates.

Other options also are on the table. The official declined to name them but others have said previously that sending some troops earlier than planned also would be considered.

There are currently some 145,000 U.S. troops in Iraq.

Also today, officials said some 13,000 National Guard troops were receiving notice to prepare for possible deployment to Iraq, which would be the second tour for several thousand of them.

The orders had been anticipated, but the specific units were not announced until Monday. They are the Army National Guard's 39th Infantry Brigade Combat Team, based in Little Rock, Ark.; 45th Infantry Brigade Combat Team, Oklahoma City; the 76th Infantry Brigade Combat Team, Indianapolis, and the 37th Infantry Brigade Combat Team, Columbus, Ohio.

The Guard units would serve as replacement forces in the regular troop rotation for the war, and would not be connected to the recent military buildup for security operations in Baghdad, the Pentagon said.

One unit would deploy in December and the others in 2008, the Army said.

"They are receiving alert orders now in order to provide them the maximum time to complete their preparations," the Defense Department said in a separate statement. "It also provides a greater measure of predictability for family members and flexibility for employers to plan for military service of their employees."

The final determination on whether the Guard units will deploy will be made based on conditions in Iraq, officials said.

The troop alerts and word of possible extensions come as Bush and Congress wrestle over legislation that would set timelines for troop withdrawals from Iraq.