> One reason is to MISLEAD!
> You tell the enemy that your efforts have been harmed so that you disclose efforts that have minimal effectiveness thereby leading your enemy into a sense of comfort and making a fresh mistake.
> It is all a Chess game.
In that case, in the last two moves Team Bush has taken the enemy's Rook (Zarkawi) and Knight (NYT--if by thus misleading the Old Grey Whore, Pinch, Keller, et al. are dispatched). There are still the Bishops (imams & mullas) and the Queen (Iran's nutcase) till OBL is checkmated. Trouble is, when the Pawns blow themselves up, they keep reappearing...hopefully this will end when the enemy's back row is eliminated...and well before one of his Pawns converts to Queen.
But the next move belongs to Bush.