Shakir worked in Kurram Agency until 2004, when he was ejected by tribal elders following a mosque bombing.

That mosque bombing followed a car bomb on Thursday that killed at least 10 people in Najaf.

Military officers in Iraq and at the Pentagon said both the army and national police responded rapidly in the hours after the mosque bombing.

However mosque bombings are not limited to Iraq.

Sunni leaders are doing themselves no credit by seeming more upset over the revenge attacks than over the mosque bombing.

Other mosque bombings in Iraq, both before and after the February 2006 bombing, have been part of the conflict between the country's groups of Muslims.

Middle Eastern government officials also say his group was behind the mosque bombing and the attack on the sheik.

But the mosque bombing was far from Yousef's most audacious encore to New York.

Al-Zarqawi purportedly declared an all-out war on Shiites while claiming responsibility for Shiite mosque bombings.

They claimed responsibility for series of mosque bombings which killed at least 74 people the same month in Khanaqin.