Former U.S. soldiers lament the violence in Iraq’s Anbar province, whose current tragic crisis began during the U.S. military occupation but is one that the U.S. can do little about now

Mushtaq Muhammed / Reuters Mourners chant as they carry coffins of victims killed by a suicide bomber in the holy city of Karbala, Iraq, on Jan. 10, 2014

For nearly a week, media reports from Iraq were eerily similar to those half a decade ago: fierce clashes had erupted between Iraqi troops and al-Qaeda insurgents in Anbar province. A wide expanse of farmland and desert that extends from the western Baghdad suburbs to the Syrian border, Anbar was the scene of some of the most brutal fighting of the Iraq War, in which more than 1,300 American troops lost their lives along with nearly 10,000 Iraqis.

The news that hit many American veterans the hardest was that fighters affiliated with al-Qaeda had taken control of Fallujah, Anbar’s second largest city, where the U.S. fought two large, bloody battles in the spring and fall of 2004. “At the moment, there is no presence of the Iraqi state in Fallujah,” a local journalist, who was not named for safety reasons, told the Washington Post. “The police and the army have abandoned the city, al-Qaeda has taken down all the Iraqi flags and burned them, and it has raised its own flag on all the buildings.”

But even as government forces lost control of Fallujah, there were glimmers of hope out of Ramadi, Anbar’s capital. Ahmed Abu Risha, a tribal leader who allied with U.S. troops and fought al-Qaeda in 2007, announced that tribal fighters, partnering with Iraqi police, were succeeding in driving insurgents out of Ramadi. “All the tribes of Anbar are fighting against al-Qaeda,” Abu Risha said. “We are happy this fight is taking place. We will confront them face to face, and we will win this battle.” Although the fighting continues, the latest reports suggest that Iraqi police and tribal militias have retaken most of Ramadi.

In the fall of 2010, the last time I was in Iraq, I traveled to Anbar with Bobby Ghosh, TIME’s former Baghdad bureau chief and current international editor. We entered Fallujah at the invitation of a tribal sheik who showed us a city teeming with policemen — all members of his tribe. There was little violence and constant construction. After destroying much of the city during the battles of 2004, the U.S. fueled a building boom through grants, and Fallujah’s physical scars were slowly melting away. Three years later, the Iraqi army is mobilizing in the deserts outside the city, and in order to drive out al-Qaeda, they may destroy it once again.

There are three main explanations for Anbar’s recent descent into chaos. Some blame the failure of the Obama Administration to negotiate a “status of forces” agreement that keeps at least a few thousand troops inside the country. The civil war in neighboring Syria has allowed the Islamic State of Iraq and Greater Syria (ISIS), an al-Qaeda-linked insurgent organization, to organize and equip before spilling across the Iraqi border. Others point a finger at Iraqi Prime Minister Nouri al-Maliki and his Shi‘ite-dominated administration’s poisonous relationship with Iraq’s Sunni minority.

The unraveling of Anbar, an overwhelmingly Sunni province, has been a slow, winding tragedy, caused partly by all three factors. Some American experts who have studied and operated in Iraq believe the latest clashes in Anbar have revealed the insurmountable fault lines in Iraq’s political system. Others are cautiously optimistic that today’s battles can give way to some future stability. Nearly all agree that the latest violence is another heartbreaking chapter for a province where so many Americans and Iraqis fought and died, a place where they lost a great deal for fragile gains that today are in grave danger of disappearing.

After serving two combat tours where he fought at the spearhead of the 2003 invasion and in the 2004 Battle of Najaf as a Marine platoon commander, Massachusetts native Seth Moulton stayed in the country to work for David Petraeus, who was then in charge of rebuilding the Iraqi army. After his third tour, Moulton returned home to begin graduate school, but when Petraeus returned to Iraq to command all U.S. forces during the surge, Moulton went with him. In 2007 and 2008, Moulton and a small team of Marines traveled around areas south of Baghdad, forging alliances with sheiks and local leaders against the insurgency.

Shortly after arriving back in the country, Moulton and his team traveled to Anbar to study the lessons of the growing Awakening movement, where Sunni leaders were partnering with U.S. forces to overthrow al-Qaeda. The team then flew to Diwaniyah, a city south of Baghdad, to forge alliances in that area. “We didn’t come in with this grand plan or this American strategy,” Moulton says. “We came in with some principles, and we got the Iraqis to agree to our goals, then largely let them show us how we could achieve them and work together.”

Like many veterans, Moulton is saddened by the return of violence in Iraq. “It’s sad for those of us who were there, who lost years and friends and parts of our lives in Iraq,” he says. “It’s hard to see it for the Iraqis, many of whom are still my friends and who had this real taste of freedom and a chance to live better lives, and now must see that evaporating before their eyes.”

New Yorker Zach Iscol commanded a large combined-action platoon of U.S. Marines and Iraqi soldiers in 2004. He and his troops fought in some of the most intense combat since Vietnam in Fallujah and operated throughout Anbar. After leaving the Marines, Iscol returned to Anbar as a filmmaker in 2008 and 2009 and explored the fragile peace that developed from the Awakening movement in his film, The Western Front. “We were able to see how strong these bonds had become between the American military and the tribes,” Iscol says. “There was a real sense of brotherhood and shared sacrifice. There was a lot of talk about how it would never go back to the base of al-Qaeda.”

But when American troops pulled out, those allies Iscol fought with had to fend for themselves. “We built alliances; we had a lot of people who stuck their necks out, who are being targeted, either by Maliki’s government or they’re being targeted by al-Qaeda,” he says. “The shame of it is those are people who love their country, love the folks in the military and fought by our side. That’s the heartbreaking piece that people are not talking about today.”

Anbar’s unraveling began shortly after the final U.S. troops left the country in December 2011. The last Americans were gone for barely one day when al-Maliki began going after his political opponents. “One of the things that caused the surge to succeed was the evenhanded treatment of all parties,” says Peter Mansoor, a professor of military history at Ohio State University, who commanded a brigade in Iraq in 2003 and 2004 and later served as General Petraeus’ executive officer during the surge. “Once U.S. forces left, and with it our influence in Iraq, the treatment by al-Maliki of other groups became much more one-sided.”

Some commentators have argued that if the U.S. had left troops in the country beyond 2011, they could have helped in the fight against al-Qaeda. Mansoor points out that, at the very least, a small number of troops would have given the Americans a reason and leverage to try to influence al-Maliki. “It gave us a seat at the table,” Mansoor says. “Now, there’s no U.S. general in country. The ambassador can request meetings, but there’s no reason to have a routine, regular meeting with Maliki where he can present his concerns.”

Ryan Crocker, the U.S. ambassador to Iraq during the surge, agrees, but feels the U.S. can exert influence even today, with no troops in the country. “Diplomacy is a powerful weapon when it’s employed,” Crocker says. “I would hope to see the Administration wake up and see the danger and become much more actively engaged at a much higher level politically. The President can do it by phone. They’ve got to know we’re serious about the relationship.”

Moulton, who is running for Congress in Massachusetts as a Democrat, wants to see the U.S. have a deeper diplomatic engagement with Iraq. “At the end of the day, beyond the fact that it’s just personally hard to see this happening to Iraq because of the time I spent there, it’s also very dangerous for the stability of the broader Middle East,” Moulton says. “We needed then, and we still need now, more diplomatic effort. There are real, serious consequences to a failed state in Iraq that extend far beyond its borders.”

One of the main goals of the American mission in Iraq was to leave behind a capable military able to handle the country’s security threats. During the reconstruction effort, U.S. forces found more success reconstituting the military than in helping to build a functioning democracy, the ramifications of which can be seen today. “When you get to root causes, this doesn’t come down to lack of military capacity,” Peter Munson, a retired Marine officer and author of Iraq in Transition: The Legacy of Dictatorship and the Prospects for Democracy, says of the current situation in Anbar. “The symptoms are coming from Syria, but the root problems go to Iraqi politics.”

How the Iraqi government handles taking back Fallujah will tell us a lot about the country’s near future. “If they go in and indiscriminately reduce the city, that’s going to play very hard for Sunni-Shia reconciliation,” Munson says. “On the other hand, if there’s some fighting but an attempt to limit the collateral damage, and if ISIS decides to fall back, that might not inflame the bad relations as much as an all-out assault.”

The next test will come as Iraq prepares for parliamentary elections in April. If the Iraqi government can retake the city without undue bloodshed, and the al-Maliki government makes a real attempt at reconciliation, the elections could proceed peacefully. But Munson worries that bad blood from the latest Anbar clashes could lead to a low turnout among Sunnis, or a Sunni boycott altogether. Even if the Fallujah assault is successful, basic politics could also damage the elections. “He’s not going to come out on top in those elections by throwing a bone to the Sunnis,” Munson says of al-Maliki. “He’s going to come out on top in those elections by energizing his core constituency that are very happy to see a strong policy against the Sunni tribes, especially when bombs are going off in Baghdad and in some of the Shia areas that are seen to come from Anbar.”

Despite the deep challenges Iraq faces, Crocker sees reason to be cautiously optimistic. One of the most experienced diplomats of his generation — he served in Beirut during the Lebanese civil war and as ambassador to Kuwait, Syria, Pakistan and Afghanistan — he has seen his share of clashes between factions within a country. “I never want to be optimistic about the Middle East,” he says, “but al-Qaeda made some giant mistakes, building on the giant mistake they made in 2005–06, when they terrorized those who needed to be their allies and turned them against them.”

Crocker points to Abu Risha’s defiant statements against the ISIS insurgents as reason to hope that al-Qaeda can be driven once again from Anbar and the province can return to some form of stability. What happens after that is up to al-Maliki and the Iraqi government. “The show will go on. Al-Qaeda is not going away; sectarian tension in Iraq is not going away,” Crocker says. “This is maybe Act 2 Scene 1 that I think will end in a provisional triumph for the so-called good guys. But boy, it’s not the end of the play.”