The U.S. announced Wednesday that all active-duty Army troops in Iraq and Afghanistan will serve 15-month tours -- three months longer than the usual standard -- beginning immediately.

"This policy is a difficult but necessary interim step," U.S. Defence Secretary Robert Gates told a Pentagon news conference.

It's the latest move by the Pentagon to cope with the strains on the military, which is fighting two wars simultaneously and maintaining a higher troop level in Iraq as part of President George Bush's revised strategy for stabilizing Baghdad.

"Our forces are stretched, there's no question about that," Gates said.

  • Related:

The move does not affect the Marines, whose standard tour is seven months, nor the Army National Guard or Army Reserve, which will continue to serve 12-month tours.

Gates said the new policy also seeks to ensure that all active-duty Army units get at least 12 months at home between deployments. That would allow the Pentagon to maintain the current level of troops in Iraq for another year. Gates added, however, that there has been no decision on future troop levels.

Some units had already been extended beyond 12 months by varying amounts. The new policy will make deployments more equitable and more predictable for soldiers and for their families, Gates said.

He added that if the standard tour length was not extended to 15 months, the Army would have been forced to send five brigades to Iraq before they completed 12 months at home.

"I think it is fair to all soldiers that all share the burden equally," Gates said.

With a report from the Associated Press