The Post's Louisa Loveluck explains the significance of U.S.-backed forces claiming victory over the Islamic State in Raqqa, Syria. (Sarah Parnass,Joyce Lee,Osman Malik,Louisa Loveluck/The Washington Post)

The U.S.-led coalition said Friday that the capture of the Islamic State’s onetime Syrian capital of Raqqa marked a turning point in the fight against the extremist group, effectively declaring an end to the military operation there.

A U.S.-backed force known as the Syrian Democratic Forces, or SDF, has been clearing the final pockets of resistance in the city since proclaiming victory over the Islamic State on Tuesday.

“Daesh’s loss of Mosul and now Raqqah are turning points for the terrorist organization whose leaders grow ever more distant from a dwindling number of terrorist adherents,” the coalition said in a statement, using an Arabic acronym for the Islamic State.

Three years after seizing a swath of land the size of Belgium across Syria and Iraq, the Islamic State no longer holds any major cities and is clinging to only one sizable stretch of territory spanning the border between the two countries. 

The group had used its self-declared caliphate to raise revenue through taxes, extortion and the sale of oil. Analysts said the group would now shift back to its guerrilla roots, seeking to capitalize on unresolved social divisions across Syria and Iraq, a strategy that allowed it to win a degree of popular support in the first place.

The Al-Na'im roundabout after its liberation in central Raqqa, Syria. ISIS extremists used the roundabout to perform public executions, beheadings and crucifixions during their three-year rule of the city. (Youssef/Epa-Efe/Rex/Shutterstock)

The battle for Raqqa began in June, with the SDF advancing on foot as U.S.-led coalition airstrikes pummeled Islamic State positions from above.

Much of the city now lies in ruins. The water supply and electricity grid have been shattered. According to monitoring groups, more than 1,000 civilians were killed in the fight.

The SDF used a news conference Friday inside Raqqa’s main stadium to call on the international community to commit the necessary funds to support an incoming civilian council and return the city to a habitable state

“We call upon all countries and peace-loving forces and all humanitarian organizations to participate in rebuilding the city and villages around it and help in removing the scars of war that were inflicted by the Islamic State,” said Talal Sillo, a spokesman and senior SDF commander.

The full cost of reconstructing Raqqa city remains unknown and international donor funding is publicly earmarked only for short-term projects.

More than 270,000 people had fled the city since June. Many are camped across a network of poorly supplied displacement camps with little hope of being able to return home anytime soon. 

The coalition used its victory statement to push back at criticisms that the civilian cost had been too high and that the ground operation was led by a mainly Kurdish force that did not represent the demographics of the city it came to liberate.

“They fought tenaciously and with courage against an unprincipled enemy, taking great care to move the population trapped by Daesh away from the battle area and minimize civilian casualties,” said Brig. Gen. Jonathan Braga, the coalition’s director of operations. He described the SDF as an “ethnically diverse force” led by “local elements.”

Although the SDF features a substantial number of Arab fighters, its operational structure is dominated by Kurdish militias linked to the Kurdistan Workers’ Party, or PKK, which is designated as a terrorist organization in neighboring Turkey.

The fighting force celebrated victory Thursday with a news conference in a central square once used by the Islamic State to showcase beheadings. Behind the gathered fighters was a banner of Abdullah Ocalan, a divisive Kurdish nationalist leader who has been jailed as a terrorist in Turkey. 

The image heightened fears among some Arab former residents that their city could now be dominated by a force toward whom they harbor deep suspicions and resentments.

“Where is the ‘Arab ingredient’ that the SDF spoke so much about,” Khalaf Al-Malla, an activist now living in northern Syria, wrote on his Facebook page, describing Ocalan as the city’s new “caliph.” 

“Why don’t they represent them as a partner in victory? It seems they just sent them to die in the fight against ISIS.”

Sillo said 655 local and international SDF fighters had lost their lives during the four-month battle for Raqqa. “Our victory is one against terrorism,” he said.