WASHINGTON &

It was a particularly bad week, even by Iraq standards: a spectacular bombing, a high-profile kidnapping, more U.S. casualties. Still, the No. 2 American commander there says, "Security across Iraq is generally improving."




That's partly because commanders believe they are gaining traction against extremist fighters. And with the highest number of U.S. troops there so far in the war &

now 162,000 &

they are trying to make the most of recent gains.




Army Lt. Gen. Ray Odierno, the day-to-day commander of operations in Iraq, said Friday that coalition forces are planning "quick strike raids" aimed at smashing al-Qaida and other insurgents in far-flung parts of the country who have evaded recent operations.




"If we can, we want to finish them off," Odierno said of al-Qaida.




"We have a chance to really go after them and defeat them," he said.




Speaking to Pentagon reporters by video conference from Baghdad, he also said commanders are planning in April to start withdrawing troops sent in as part of President Bush's buildup &

and complete the drawdown to pre-escalation levels by August 2008.




Military operations launched since the escalation have helped coalition forces capture and kill insurgent leaders, disrupt their operations and supply lines and retake some territory from them in main population centers, he said.




Officials believe extremists are trying to regroup in northern Iraq, where American troop presence is much lighter, after being driven from strongholds in and around Baghdad. Odierno acknowledged the devastation of this week's spectacular quadruple bomb attack in two northern Iraqi villages that officials say killed at least 500 people.




The military has calmed areas of the country in the past, then moved on to other places only to find insurgents return to the just-calmed area. Commanders have said the extra troops from the buildup are helping them fight that problem now.




It also is not a new development that as coalition forces fight a problem in one area, militants rise up in another. Odierno did not answer the question of whether he has enough troops to go after regrouping insurgents in isolated locations.




"Due to the constant pressure and depletion of their leadership, extremists have been pushed out of many population centers and are on the move, seeking other places to operate within the country," he said.




"As a result, we are now in pursuit of al-Qaida and other extremist elements, and we'll continue to aggressively target their shrinking areas of influence," he said.




"Over the coming weeks, we plan to conduct quick-strike raids against remaining extremist sanctuaries and staging areas," he said, adding that the large majority of strikes will be done jointly with Iraqi forces.




The effort began Tuesday, he said, when about 16,000 U.S. and Iraqi soldiers began a sweep through the Diyala River valley north of Baghdad in pursuit of Sunni insurgents and Shiite militia fighters driven out of strongholds in recent weeks.




Odierno also said commanders are planning to withdraw the five extra brigades of soldiers sent for the buildup when their 15-month tours of duty end. The brigades arrived roughly one a month from January to June.




Asked if they would be able to leave the same way starting next April, he said he was "not willing to quite say that yet" because top commander Gen. David Petraeus may decide to send replacements for some, depending on the security situation.




But "right now, our plan is not to (replace) those units," he said.




Odierno also said there has been a shift in calculations on who is causing the violence in Iraq. The military estimates that in July, 52 percent of the violence across the country was caused by al-Qaida and Sunni insurgents and 48 percent by Shiite extremists &

compared with January when they say Sunnis and al-Qaida accounted for 70 percent.




He said that reflects both a decrease in al-Qaida's ability to conduct operations and a surge in Shiite violence, with support in weapons and training from Iran.




Nevertheless, he said, the troop escalation and resulting new operations have improved security and bought time for Iraqis to try to make progress toward political reconciliation. Those gains can't be held indefinitely without improvement in the political area, he said.




"I do believe that it's sustainable for a period of time, but it's not a blank check, it's not for a long period of time," he said.




U.S. lawmakers have long complained that Iraqi officials are not taking advantage of U.S. efforts and making enough progress, and recent polls show the American public agrees.




To promote reconciliation, U.S. commanders are pushing to negotiate more agreements with Sunni groups in a program started in recent months in which some militants agreed to fight al-Qaida instead of coalition forces, with an eye toward eventually joining Iraqi government security forces.




"With the Sunni insurgency, for the most part ... they have decided that we're going to go with al-Qaida, or they've decided to reconcile with the government of Iraq and they're reaching out to coalition forces" for such agreements, he said.




He said talks are under way in a number of areas and it is "important to get these groups reconciled with the government of Iraq over the next several months."