Is "clear and hold" enough?

"As the United States entered the fourth year of occupying Iraq, it had 130,000 troops battling a Sunni Arab insurgency. Based in a community that is no more than 20 percent of Iraq's population, the Sunni Arab insurgents cannot prevail militarily. But they cannot be readily be defeated either. The U.S. can clear insurgents out of Sunni cities, but it has insufficient forces to hold the territory. Pushed out of one area, the insurgents move to another and return when the Americans move on."
--Peter W. Galbraith, The End of Iraq


But how can security forces protect Iraqi citizens from suicide bombers?

‘ “We need more security forces to protect us,” a shopkeeper who would identify himself only as Ali said in the aftermath of an attack in the Sadr City section of Baghdad.

The persistent violence in Mosul and Nineveh underscores the broader turmoil afflicting Iraq. But it also reflects the region’s unique mixture of insurgency and ethnic tensions between Kurds and Arabs, as well as a proliferation of criminal gangs, that makes the north the most dangerous part of the country.

That was supposed to change last spring, when 4,000 American troops joined more than 25,000 Iraqi security personnel to clean out Mosul’s neighborhoods one by one. Just as significantly, a Sunni Arab political bloc won in January’s provincial elections, giving the Arab citizens of the north proportional representation for the first time and, it was hoped, defusing antigovernment sentiment and support for insurgents. It has not turned out that way.’