Kurdish forces backed by US air strikes seized the northern Iraqi town of Sinjar from Islamic State on Friday, in one of the most significant counter-attacks since the militants swept through the north last year.
"ISIL defeated and on the run," the Kurdistan regional security council said in a tweet, using an acronym for Islamic State. It said Kurdish peshmerga forces, which led the operation, had secured Sinjar's wheat silo, cement factory, hospital and several other public buildings.
Sinjar is home to Iraq's Yazidi minority who suffered at the hands of Islamic State when it overran the area in August 2014, systematically slaughtering, enslaving and raping thousands.
Iraqi Kurdish regional President Massoud Barzani also declared victory in an offensive that could provide critical momentum in efforts to capture the western provincial capital Ramadi, and Mosul in the north, an Islamic State bastion.
"The liberation of Sinjar will have a big impact on liberating Mosul," Barzani, who personally oversaw the offensive, said atop Mount Sinjar, overlooking the town.
The recapture of Sinjar from Islamic State came as evidence grew that the group had suffered another setback with the probable death in an air strike in northern Syria of Jihadi John, a Briton who had appeared in videos showing the beheadings of American and British hostages (See: IS executioner 'Jihadi John' killed in drone strike).
In the Sinjar area itself, the operation severed vital supply routes used by Islamic State to move fighters, weapons and oil and other illicit commodities that provide funding for its self-proclaimed caliphate.
Civilians appeared to have fled the town before the operation began. But it was still not clear if most Islamic State militants had carried out a tactical withdrawal.
Peshmerga forces and fighters affiliated with the Kurdistan Workers' Party (PKK), both of which include Yazidis, entered Sinjar on Friday after cutting it off from east and west.
The Kurdistan council said peshmerga forces had entered Sinjar "from all directions" to begin clearing remaining insurgents.
A Reuters correspondent saw hundreds of peshmerga fighters walking into the town and along a main road without facing immediate resistance.
Kurdish commanders expressed concerns that some insurgents were hiding and would blow themselves up as the peshmerga advanced.
The number of Islamic State fighters in the town had risen to nearly 600 in the run-up to the offensive, but only a handful were left in Sinjar on Friday, said Brigadier General Seme Mala Mohammed of the peshmerga.
Islamic State, made up of Iraqis, other Arabs and foreign fighters, poses the biggest security threat to OPEC oil producer Iraq since a US-led invasion toppled Saddam Hussein in 2003.
Campaigns to contain Islamic State have moved slowly in Iraq, where sectarian divisions and corruption have hindered military progress.