This provides some relevant background information on the insurgents operating in Mosul.
Link to Full Article
By RICHARD A. OPPEL Jr. - New York Times
MOSUL, Iraq - After a three-hour firefight here in northern Iraq this month, American commanders were surprised to learn that one of the 22 insurgents they had killed was a Saudi. Even more intriguing, one of the principal leaders of the insurgency attended the funeral, the commanders learned.
This was Mohammed Sharkawa, who is described as a former member of the Ansar al-Sunna organization who now directs several hundred insurgents here in Mosul. As one commander, who said Mr. Sharkawa had killed several of his own cousins, put it, he is "a brutally ruthless criminal, almost like a mob wiseguy who started whacking dudes." [...]
"Their common aims are to disrupt the elections process and delegitimize the existing government," said Col. Tom Knight, the deputy commander of American troops in northern Iraq. "There's no denying it has been a successful tactic and that it has discouraged local support." [...]
But the secular and jihadi wings each have a few hundred core operators in Mosul, and "the fighters who can be rented out probably number in the thousands," General Ham said.
"The hard core group is quite smart; they get others to do their work for them," the general added. "All the dumb guys are dead or in jail. The surviving leaders are very competent."