Pick up any newspaper and you'll find another politician or editorialist trumpeting the success of the surge in Iraq. Having predicted that the surge was likely to fail, some have suggested I called it wrong. Not so fast.

Sectarian violence has declined, and U.S. casualties are down. While that hardly equates to achievement of our strategic goals, it's good news. Was the rise in U.S. troop levels in 2007 the cause, or did the surge coincide with other events?

In Anbar province and other areas dominated by Sunni Arabs, violence is down because of the "Sunni Awakening." This was not a new strategy or a part of the surge. We were doing this in 2006. Arming and assisting Sunni tribal militias put al-Qaida to the sword, and largely pacified Anbar and neighboring areas.

Another blow came when the Assad government decided to stop letting al-Qaida use Syria as a staging area and a route into Iraq. A recent suicide bombing in Damascus underscores the fact the Islamic extremists pose an existential threat to the world's only secular Baathist regime. The surge didn't secure the Syrian border. Syria did.

In his new book, "The War Within," Washington Post editor Bob Woodward claims that secret assassination programs also helped put al-Qaida out of business. That may be true, but those operations certainly weren't a product of the surge.

Then there is the Mahdi army's cease-fire, first announced in August 2007 and extended in February. Moqtada al-Sadr's reasons for calling a halt to attacks on coalition forces and the Iraqi military are opaque, but no one has tied the cease-fire to the surge.

The most overlooked reason for the reduction in violence, and the most important one, is that ethnic cleansing has run its course for the time being. In September 2007, an independent commission headed by retired Gen. James Jones attributed the decrease in violence to "areas being overrun by either Shiites or Sunnis." That same month a National Intelligence Estimate also attributed diminished violence in Baghdad to "sectarian separation." John Agnew, a UCLA professor who conducted a study of satellite imagery of Baghdad, concluded sectarian violence reached its climax just as the surge was beginning.

Professor Juan Cole, an authority on contemporary Islamic movements, estimates that 700,000 to 800,000 Sunnis were ethnically cleansed from Baghdad from June 2006 to September 2007. The U.N. Assistance Mission in Iraq reports that more than 2 million Iraqis are living as refugees in neighboring countries while 2.7 million are displaced inside Iraq. There are more than 563,000 internally displaced persons in Baghdad, and another 103,000 in adjacent Diyala province. Compare this to a mere 1,500 or so families displaced from Baghdad in 2003 to 2005, and the scale of ethnic cleansing becomes apparent.

Sectarian violence is down because the goal of that violence has been realized.

Troop levels are not a strategy. What Gen. David Petraeus did with the troops is the new strategy. Petraeus ordered our soldiers and Marines to protect the Iraqi people. He stationed platoon and company-sized units in Baghdad's neighborhoods, instead of keeping them encamped in massive bases. He got patrols out of their armored Humvees and mixing with the population.

Ultimately, neither troop levels nor the manner in which they are employed will turn Iraq from a failing state into a success. American soldiers cannot save Iraq. Only Iraqis can do that.

Is the surge the reason for reduced violence in Iraq, or were there other causes? I have always had trouble believing that the infusion of 20,000 or 30,000 more soldiers for a few months could succeed in pacifying a nation of 27 million. Military historians will debate the question, but my verdict remains unchanged. The surge was an unnecessary exercise.

Retired Col. Thomas D. Farrell was an Army intelligence officer in Iraq from June 2005 to May 2006. He wrote this commentary for The Advertiser.