Nearly a year after sweeping across northern and western Iraq, the Islamic State group this weekend seized Ramadi, capital of the western Anbar province, routing Iraqi forces despite heavy U.S.-led airstrikes.
Ramadi is the first major city to fall to the extremist group since last summer, and the takeover came after months of steady progress by Iraqi troops, Kurdish forces and Shiite militias elsewhere in the country.
Here is a look at what the capture of Ramadi means for Iraq and U.S.-backed efforts to roll back the extremist group, which still controls vast swaths of Iraq and neighboring Syria.
WHAT IS THE SIGNIFICANCE OF RAMADI?
Ramadi is the capital of Anbar, a vast Sunni-majority region where distrust of the Shiite-led government runs deep. U.S. troops fought some of their bloodiest battles since Vietnam in Anbar during the eight-year intervention and only succeeded in rolling back militants when Sunni tribesmen and former insurgents rallied to their side as part of the Sahwa, or Awakening, movement beginning in 2006.
Since U.S. troops withdrew at the end of 2011, the Iraqi government has largely ignored the Sahwas, and Sunni anger at Baghdad has steadily grown. After Iraqi forces dispersed a major Sunni protest camp near Ramadi in late 2013, the Islamic State group and other militants captured parts of Ramadi and all of nearby Fallujah. Iraqi forces have been trying to dislodge the extremists from Anbar ever since, with little success.
Ramadi is just 70 miles (115 kilometers) west of Baghdad on a major highway linking Baghdad to Syria and Jordan. It had a population of 850,000 in 2003 but most of its people have fled the violence over the last 12 years. Just 5,000 families remained on the eve of the IS takeover, most of whom have likely fled by now.
WHAT DOES RAMADI'S FALL MEAN FOR THE INTERNATIONAL CAMPAIGN AGAINST IS?
The city's fall comes as a major blow to the Iraqi government, which has been struggling to rebuild its U.S.-trained and equipped army since its humiliating rout last summer. Prime Minister Haider al-Abadi, who assumed power after last year's IS offensive, had pledged to restructure the security forces and reach out to Iraq's Kurdish and Sunni minorities. His decision to order Shiite militias into Anbar reflects lingering doubts about the army's effectiveness and could set the stage for a renewed sectarian conflict.
The loss of Ramadi also raises serious questions about the effectiveness of U.S. air power in containing and rolling back the extremists. U.S.-led warplanes carried out 32 airstrikes in Ramadi over the last three weeks, including eight in the past 24 hours.
The defeat in Ramadi breaks a streak of successes by Iraqi forces around Baghdad and in the north, where they retook the city of Tikrit in early April. It will likely further delay the expected battle for the northern city of Mosul, Iraq's second largest, which remains firmly in the grip of the IS group.
WHAT ABOUT THE DECISION TO SEND IN SHIITE MILITIAS?
Iran-backed Shiite militias have played a key role on the ground against the IS group, but rights groups say they have also carried out revenge attacks and looted and destroyed property.
The government had hoped to rely on the army and allied Sunni tribesmen in Anbar, including the remnants of the Sahwa. Sending in Shiite militias could further alienate the local population and erstwhile tribal allies, driving them into the arms of the IS group, which presents itself as the defender of Sunni Muslims against Shiite Iran and its allies.
At this point, the government and the people of Anbar may have no other option than to rely on the militias. Already, some Sunnis in Anbar are urging the militias to come to their aid.
WHAT DOES THE LOSS OF RAMADI MEAN FOR US CREDIBILITY?
Senior Iraqi officials have long complained that the U.S. is not doing enough to aid its forces battling the Islamic State group, and Washington will likely share the blame for losing Ramadi.
Such criticism is not entirely fair. Earlier this year U.S.-led airstrikes broke a weekslong stalemate and gave Iraqi forces a key boost in capturing Tikrit. And the air campaign has helped Kurdish forces advance against the IS group in the north since last summer. The United States has also sped up the delivery of arms to Iraq, and in July will deliver the country's first and long-awaited F-16 fighter jets.
Nevertheless, many Iraqis view Iran as their greatest ally against the IS group and see the Shiite militias as the shock troops who have made the biggest difference on the ground. If the Shiite militias succeed in Anbar where the U.S.-backed army failed, Tehran looks to gain even more influence in Baghdad. That would continue a trend dating back to the 2003 toppling of Saddam Hussein, who was Iran's archenemy.
WILL AL-ABADI HOLD ONTO POWER?
The loss of Ramadi is a painful setback for al-Abadi, who had pledged a new start last year after succeeding Prime Minister Nouri al-Maliki, whose sectarian policies are widely seen as having contributed to the rise of the Islamic State group.
Until now al-Abadi could point to a string of battlefield successes, improved relations with the Kurds and local alliances with Sunnis to argue that he was slowly stitching Iraq together.
Now he will be forced to explain the loss of Ramadi despite considerable U.S. and international support. Al-Maliki, who now holds the largely ceremonial post of vice president along with two other officials, remains a major presence on the political scene and makes frequent media appearances. He is widely rumored to be seeking a comeback, and did not rule out a return to the premiership in an interview with The Associated Press earlier this year.