Today 's barrage could have been a show of force as the military steps up security against threats of intensified attacks over the Christmas holiday by Baghdad 's 14 identified guerrilla cells .
Kimmitt said the operation was a show of force as the military steps up security against threats of attacks over the Christmas holiday by Baghdad 's 14 identified guerrilla cells .
Operating and control elements shall be clearly marked, so that they are identifiable by the driver.