So far I have seen nothing to indicate that these terrorist groups suffer any harm when their leaders are killed. If anything, it seems to motivate them and we see more attacks from them, not less.

According to the Pentagon report released earlier this month, in the 3 months since al-Zarqawi was killed (June-August), the number of attacks in Iraq has increased by 24% to 792 per week compared with 641 per week during the previous 3 month period.