BAGHDAD -- The last Iraqi security forces fled Ramadi on Sunday, as the city fell completely to the militants of the Islamic State, who ransacked the provincial military headquarters, seizing a large store of weapons, and killed people loyal to the government, according to security officials and tribal leaders.
The fall of Ramadi, despite intensified U.S. airstrikes in recent weeks in a bid to save the city, represented the biggest victory so far this year for the Islamic State, which has declared a caliphate, or Islamic state, in the vast areas of Syria and Iraq that it controls. The defeat also laid bare the failed strategy of the Iraqi government, which had announced last month a new offensive to retake Anbar province, a large desert region in the west of which Ramadi is the capital.
"The city has fallen," said Muhannad Haimour, the spokesman for Anbar's governor.
Haimour said that at least 500 civilians and security personnel had been killed during the last two days in and around Ramadi, either from fighting or executions. Among the dead, he said, was the 3-year-old daughter of a soldier.
"Men, women, kids and fighters' bodies are scattered on the ground," said Sheikh Rafi al-Fahdawi, a tribal leader from Ramadi, who was in Baghdad on Sunday and whose men had been resisting the Islamic State, also known as ISIS.
He also said, "All security forces and tribal leaders have either retreated or been killed in battle. It is a big loss."
The loss of Ramadi came a day after the Pentagon said Special Operations forces, flying in helicopters that took off from Iraq, carried out a raid in eastern Syria that resulted in the death of an Islamic State leader and the capture of his wife, along with the recovery of a trove of materials U.S. officials hope will yield important intelligence on the group.
U.S. officials said recently that the Islamic State was on the defensive in Iraq, noting that the group had lost territory in Salahuddin province and in some other areas in northern Iraq near the border with the autonomous Kurdish region. Yet the fall of Ramadi shows that the group is still capable of carrying out effective offensive operations.
Anbar province holds painful historical import for the U.S. as the place where nearly 1,300 soldiers died after the U.S.-led invasion of 2003. Since the beginning of 2014, months before the fall of Mosul and the start of the U.S. air campaign against the Islamic State, the United States has been working with the Iraqi government to drive the extremist group from Anbar, sending vast supplies of weapons and ammunition and, more recently, training Sunni tribal fighters at an air base in the province.
With defeat looming in Ramadi on Sunday afternoon, the Anbar Provincial Council met in Baghdad and voted to ask Prime Minister Haider al-Abadi to send Shiite fighters to rescue Anbar, a largely Sunni province.
In response, al-Abadi issued a statement calling for the militias, known as the Popular Mobilization Forces and including several powerful Shiite forces supported by Iran, to be ready to fight. Some of the Shiite irregular units, which were formed last summer after Shiite clerics put out a call to arms, are more firmly under the command of the government, while others answer to Iran.
The involvement of the militias in Anbar had been opposed by the United States, which leads an international coalition that has been carrying out airstrikes in support of Iraqi forces. U.S. officials had worried that the militias could inflame sectarian tensions in the province and ultimately make it harder to pacify.
As they considered asking for the militias' assistance, Anbar officials met over the weekend with the U.S. ambassador to Iraq, Stuart E. Jones, to ascertain the United States' position on the issue. According to officials, Jones told the Anbar delegation that the U.S. would continue its air campaign, provided that the militias were under the command of al-Abadi, and not Iranian advisers, and that the militias were properly organized to avoid U.S. bombing runs.
At the outset of an offensive to liberate Tikrit, in Salahuddin province, in March, the Iranian-backed militias took the lead, and U.S. warplanes stayed away. Once those militias stalled, al-Abadi ordered them to retreat, which was followed by airstrikes by the U.S., an advance by Iraqi security forces, and the liberation of Tikrit.
In the wake of that victory, al-Abadi promised a new effort in Anbar, a campaign to be led by the Iraqi security forces and supported by U.S. airstrikes, with Iranian-backed militias on the sidelines. A key component of that strategy was to arm local Sunni tribesmen to fight, but that plan never materialized on a large-scale, partly because of resistance by powerful Shiite political leaders in Baghdad.
The deterioration of Anbar over the last month underscored the ineffectiveness of the Iraqi army, which is being trained by U.S. military advisers, and raised questions about the United States' strategy to defeat the Islamic State. At the same time, now that the militias are being called upon, the collapse of Ramadi has demonstrated again the influence of Iran, even if its advisers are unlikely to be on the ground in Anbar, as they were during the operation in Tikrit.
The Islamic State, which has held areas around Ramadi for nearly a year and a half, began an offensive on the city late Thursday night, and on Friday afternoon captured the provincial government headquarters.
Al-Abadi on Friday promised to send reinforcements, but only about 200 soldiers arrived from Baghdad to help resist in one of the last contested neighborhoods in the city, according to a security official in Anbar.
U.S. officials in Washington played down the situation Friday, saying it was similar to the up-and-down fighting there since the beginning of last year.
Yet the Islamic State was able to consolidate its hold of the city over the weekend and on Sunday seized one of the last government redoubts, the local operations command center. The remaining officers and soldiers had fled, and one of them reached by telephone Sunday afternoon said they were stuck in a convoy southwest of Ramadi, with Islamic State militants closing in from four sides.
Another soldier who had been stationed at the Anbar Operations Command headquarters said the forces had left behind a huge cache of weapons recently sent by Baghdad, including rocket-propelled grenades and heavy machine guns. The weapons had been supplied by both the U.S. and Russia.
"ISIS is gaining more weapons, and the battle will be harder in the future," said the soldier, who declined to give his name because he feared for his life.
Shiite militia leaders, who had mostly watched the collapse from afar, were scrambling on Sunday to mobilize their men.
Mueen al-Kadhumi, a leader in the Popular Mobilization Forces and a member of the Badr Organization, a longstanding militia with ties to Iran, said, "We have recalled all off-duty fighters to join their units as soon as possible to participate in the upcoming battle for Anbar."
Pentagon officials said Sunday that it was premature to declare that Ramadi had fallen.
"We're continuing to monitor reports of tough fighting in Ramadi, and the situation remains fluid and contested," said Col. Steven H. Warren, a Defense Department spokesman.
Coalition warplanes carried out more attacks on Islamic State targets in Iraq, with seven airstrikes on militant positions in or near Ramadi over the weekend, according to official statements. But the advance by Islamic State fighters was evidence again that U.S. air power alone could not hold territory for the Baghdad government, or dislodge the militants, without an effective Iraqi force on the ground.
The wife of the Islamic State's senior financial officer remained in U.S. custody in Iraq on Sunday. Umm Sayyaf was captured during the Saturday raid into Syria that killed her husband, Abu Sayyaf, and about a dozen militant fighters.A senior U.S. official, who spoke on the condition of anonymity to discuss the continuing investigation, said Abu Sayyaf's death was likely to cause only a minor disruption in the Islamic State's broader financial operations, which include black-market sales of petroleum products.
"This will be short-lived," the official said. "Organizations like this are designed to have succession plans."
Reporting was contributed by Omar al-Jawoshy and Falih Hassan from Baghdad; an employee of The New York Times from Anbar province; and Eric Schmitt and Helene Cooper from Washington.