The dust storm swallowed the horizon and then the soldiers, who leaned into the windy blur to load rucksacks onto vehicles pointed homeward. At 3:30 a.m. the next day, their Army battalion would roll out under the cover of darkness, concluding their mission to advise and train Iraqi security forces in Anbar province.

The swath of western Iraq the battalion was leaving behind has seen the bloodiest points of the war, but also some of the most promising. Since the war began, 1,332 U.S. troops have died in Anbar, nearly one in three of all U.S. fatalities. But not one has been killed in action in the province in more than two years.

In 2006, there were 1,129 insurgent attacks in Anbar; this year there have been 333. The provincial police force, nonexistent five years ago, employs 32,000 officers.

Those numbers are cited by the Americans now leaving Iraq as cause for optimism. But the Iraqis who will stay in Anbar have been taking a darker view of 2012 — wondering whether the province is in the clear or merely in the eye of a storm.

Shaken confidence

A stark, scrubby expanse of territory populated almost entirely by Iraqi Sunnis, Anbar makes up a third of the country’s land area and houses 5 percent of its population. In 2004, the searing battles of Fallujah followed the killing and mutilation of four civilian contractors. Al-Qaeda in Iraq flourished in Anbar in 2005 and 2006, until tribal leaders and the U.S. military formed the Sunni Awakening to suffocate the terrorist insurgency.

Lt. Col. David S. Doyle first set foot in Anbar more than eight years ago. As he finished packing up his office at Al Asad late last month, he described the progress made in shifting responsibility for training Iraqi forces from the United States to the Iraqis themselves.

“We got to the point where U.S. trainers were stepping further away,” said Doyle, commanding officer of the departing battalion, part of the 2nd Brigade of the 82nd Airborne Division. “The Iraqi training is now self-sustaining, and their army is moving slowly away from policing functions. The next barometer is how the police do out here.”

But high-ranking U.S. and Iraqi officials admit that the police force has a long way to go and that running the development program will be more challenging under the State Department, which is allotting fewer than 200 advisers based at three sites to stay in touch with 18 provinces.

Despite the reduction in violence over the past five years, recent tremors have shaken Anbar’s confidence. Last month, gunmen massacred 22 pilgrims in western Anbar and insurgents assaulted a government compound in the provincial capital of Ramadi. Last Monday, men dressed as officers stormed a police station in al-Baghdadi, detonated bombs, took hostages and kept authorities at bay for three hours.

“The Iraqi police and army forces are in dire need of aid from the U.S.,” said Eifan al-Issawi, head of the provincial committee of security and defense. Ongoing training is “not enough. We need continuous support for our forces because al-Qaeda is not an easy enemy and should not be taken lightly.”

Brig. Gen. Khaled al-Dulaimi, the director of the training center, said that Iraqi security forces are ready to protect the country but still depend on the United States to provide gear, logistical support and assistance through contractors, who Dulaimi says have proved unreliable.

“If a student does not have good air conditioning, he will not be committed to the course,” Dulaimi said as he drank tea in his office. “A few weeks ago, we stopped all practice and lectures and stopped receiving recruits for 20 days when the generators broke down.”

‘Finishing off what we started’

The morning after the dust storm, the battalion crept out of Anbar over terrain once sown with improvised explosive devices, past checkpoints manned by the Iraqi army. With the departure of the 800-member unit, only 2,500 U.S. troops remain at Al Asad Air Base; across Iraq, as the American drawdown accelerates, an average of 500 U.S. forces are exiting the country every day.

The 93-vehicle convoy skirted the Ramadi compound of Sunni Awakening leader Ahmed Abu Risha, who says Anbar is uniquely vulnerable because it shares a 220-mile border with Syria. Risha accuses the Syrian regime of sponsoring recent insurgent attacks to distract from its own unrest.

“We respect the American Army’s mission to fight terrorism and the results of it . . . but the democratic system which exists now has failed to provide security and services for Iraqis,” said Risha, twirling a strand of worry beads in his office.

Next, the convoy passed Fallujah, where some residents think Anbar is threatened from both outside and inside Iraq.

“The United States is handing Iraq to Iran on a golden platter,” said taxi driver Ali al-Dulaimi, 45.

“Our country is in danger of being divided,” said teacher Hadeel Ahmad, referring to unsteady relations between her minority Sunni province and the Shiite-led central government.

Before the U.S. invasion, there was one cemetery in Fallujah. Now there are seven, according to Saadoun al-Shaalan, vice chairman of the Anbar provincial council, who thinks the initial instability wrought by the U.S. presence has not been fully remedied.

From the roadside, Iraqis watched the battalion’s convoy lumber along at 35 mph under the afternoon sun. Bravo Company Cpl. Scott Bryant, 34, returned their gaze from inside one of the vehicles. Bryant first deployed to Iraq during the 2007 “surge,” securing buildings in anarchic Baghdad, laying a foundation of stability. He, like his commanders, sees institutional order and a growing democracy from the windows of the mine-resistant vehicle.

In 2007, “you’d be lucky to find 30 rounds in an entire police force,” Bryant said, referring to ammunition. “Now the guys are a lot better and it’s more hands-off. . . . We’re finishing off what we started a long time ago.”

Shortly after noon, on the roadside east of Fallujah, an Iraqi teenager was repairing a bike tire. As Bryant’s vehicle passed by, the boy lifted his head, then his arm, and appeared to wag a single digit toward the convoy.

“Did you see that kid give us the finger?” asked a soldier in the front of the vehicle.

No one answered. The exhausted men of Bravo Company had closed their eyes to rest.

Special correspondents Uthman al-Mokhtar in Fallujah and Asaad Majeed in Baghdad contributed to this report.