Iraqi Kurdish leader Massud Barzani has announced the "liberation" of the town of Sinjar from the Islamic State group, the latest in a series of setbacks for the jihadists.
The operation was led by the autonomous Kurdish region's peshmerga forces, but also involved fighters from the Yazidi minority, which IS targeted in a brutal campaign of massacres, enslavement and rape.
The offensive cut a key supply line linking jihadist-held areas in Iraq with those in Syria.
Across the border, the Syrian Democratic Forces coalition said it had also delivered a blow to IS by driving the jihadists out of Al-Hol, an important village on their Iraq-Syria supply route.
The gains against IS are the latest sign that the jihadist group, which won a series of victories in a stunningly rapid offensive in Iraq last year, is now on the defensive.
In remarks on Friday (local time), US President Barack Obama expressed satisfaction with efforts against IS, saying the group's expansion has been curbed.
"From the start, our goal has been first to contain, and we have contained them," Obama said.
Barzani, the president of Iraqi Kurdistan, told a news conference: "I am here to announce the liberation of Sinjar."
His remarks also made clear that political conflict over Sinjar would be likely to follow the military battle for the town.
"Sinjar was liberated by the blood of the peshmerga and became part of Kurdistan," Barzani said.
Baghdad, which has long opposed Kurdistan's desire to incorporate a swathe of disputed northern territory, is unlikely to welcome that idea.
Earlier in the day, hundreds of Kurdish fighters, dressed in camouflage uniforms and armed with assault rifles and machineguns, moved into the town on foot
Carrying the Kurdish region's flag, they fired into the air and shouted "Long live the peshmerga!" and "Long live Kurdistan!"
Inside Sinjar, many houses and shops, a petrol station and the local government headquarters had been destroyed.
Burned out cars sat in the streets, while barrels apparently containing explosives had been left behind.
The huge task of clearing Sinjar of bombs planted by IS remains, and there is also the possibility of holdout jihadists, who have kept up attacks even after other areas in Iraq were said to have been retaken.
The US-led coalition carried out upwards of 250 strikes in support of the Sinjar operation, killing an estimated more than 200 IS fighters.