Explosions were heard in Baghdad (search) early Wednesday. The U.S. military said it was conducting an anti-rebel operation called Iron Justice.

American commanders have said they had planned operations over the Christmas period after receiving intelligence that there might be rebel attacks. Since the capture of Saddam Hussein (search) on Dec. 13, the 1st Armored Division (search) has conducted raids on rebel cells in Baghdad.

Asked about the repeated explosions, a military spokeswoman said on condition of anonymity that operations were under way. She said the operations included "aerial activity and artillery."