The U.S. military says three Marines were killed in combat operations Thursday in Anbar province.
The military made the announcement Friday. Further details were not provided.
Earlier, the military said coalition forces detained nine suspected terrorists in Mosul, Baghdad, and near Ramadi and Salman Pak. It said the raids Friday were meant to disrupt operations of al-Qaida in Iraq.
In other news, an active duty U.S. Army officer said the United States faces possible defeat in Iraq and he blamed that prospect on American generals.
Lieutenant Colonel Paul Yingling's comments came in an opinion column in Friday's Armed Forces Journal - a publication of The Army Times company. The lieutenant colonel said generals underestimated the strength of the enemy and overestimated the capabilities of Iraqi forces.
He also charged that the military leadership failed to provide Congress and the public with an accurate assessment of the conflict.
When asked for reaction, a U.S. military spokesman is quoted as saying the lieutenant colonel was expressing his personal opinions - and that the Multinational Force in Iraq is focused on executing the mission at hand.
Some information for this report was provided by AP.