There is some good news coming out of Iraq. The interim government has the support of most Iraqis. The international community is getting more involved. Money for the reconstruction effort is moving faster. But all this will mean nothing if Iraq's central problem -- a pervasive lack of security -- remains unsolved. Unless this changes soon, positive trends will turn negative. The new government will be seen as ineffectual, reconstruction will remain halting, radical militias will gain ground and there will be no elections in January. This will end in either a low-level civil war or military rule, possibly both.

Ayad Allawi, Iraq's new interim prime minister, and Defense Minister Hazim Shaalan have hinted at the possibility of imposing martial law. This is understandable, as long as it's temporary. (Syria has been in a state of emergency for 40 years.) But along with tough measures, Allawi will have to do something the United States could never bring itself to do: talk to the insurgents.

The Bush administration has never really understood the security problem in Iraq. To do so would require that it face up to its own mistakes. The original sin of U.S. postwar policy remains the decision to go into Iraq with too few troops. A larger presence would have intimidated and thus deterred some of the opposition and, in places such as Najaf and Karbala, forestalled the rise of local militias.

But the second important mistake has been to discount the size of the insurgency and its local support. For many in the administration it was an article of faith that Iraqis would welcome the American occupation. So it was impossible for them to accept the idea that ordinary Iraqis could be helping the guerrillas. That's why Donald Rumsfeld always dismissively referred to Iraqi militants as a bunch of "dead-enders." Administration officials objected to the use of terms such as "insurgents," and claimed that most of the troublemakers were foreign terrorists.

As has happened so many times regarding Iraq, ideology clouded analysis. The best-equipped, best-trained army in the world has not been able to crush or even find the "dead-enders," whose operations have grown in size, skill and organization. Fourteen months after the fall of Baghdad, Iraq's main airport remains closed, the road from the airport to Baghdad is a free-fire zone, several other key routes linking the country are extremely dangerous, and attacks on infrastructure, civilians and troops are a daily occurrence.

"There is no doubt that the insurgents have local support," says Ahmed Hashim, a professor at the Naval War College who spent several months in Iraq last winter studying the insurgency while attached to the U.S. Army. "They melt into neighborhoods. People do not inform on them. These are all telltale signs of local support." Hashim says that the insurgency is made up of Baathists, Islamists, hard-core Iraqi nationalists and a significant number of foreign terrorists. "Even the foreigners have some tacit support from people," Hashim says. The glue holding them together, he argues, is nationalism and anti-Americanism.

The Iraqi mood may be changing, and this political shift provides the best opportunity the coalition has to win this guerrilla war. The interim government has public support. The recent attacks appear to be unpopular. Sunni clerics and tribal leaders have denounced the violence, as have almost all political parties. Allawi should capitalize on this support by moving aggressively now.

The only successful strategy in dealing with insurgencies has been to separate them from their local support. That means offering political, social and economic bounties to those in the Sunni community who are tacitly backing -- or at least not opposing -- these attacks. This means co-opting clerics, tribal chiefs and former Army officers.

This strategy would isolate the most die-hard Iraqis and foreign terrorists. And they would then have to operate within less cooperative communities. Crushing this smaller group will remain tough, but counterinsurgency warfare will more likely succeed once the guerrillas have been isolated.

Some conservatives were apoplectic when U.S. forces made a deal with the insurgents in Fallujah. This strategy, they would argue, is Fallujah writ large. Actually, it's closer to the manner in which the Army handled the challenge from Moqtada Sadr in the south, using a mix of military strikes and bribes to wean away his support. Anyway, what is the alternative? The occupation, in the latest Coalition Provisional Authority poll, has 2 percent support among Iraqis. The CPA itself has inched up to 8 percent support. With those kinds of numbers, any harsh offensive operation by American troops is going to produce more insurgents than it kills. And for the immediate future, most counterinsurgency operations will remain largely American affairs.

The United States has made some strides in Iraq over the past month because it has reversed many of its most damaging policies. Prodded by the Iraqi government, it must now make this final reversal.