Iraqi forces on Sunday launched an assault to retake the northern city of Tal Afar from the Islamic State group, after ousting the jihadists from Mosul last month.
Tal Afar lies around 70 kilometres (45 miles) west of second city Mosul, which Iraqi forces recaptured in early July in a major blow to the jihadists.
In a televised speech early Sunday, Prime Minister Haider al-Abadi, dressed in military uniform and standing in front of an Iraqi flag and map of the country, announced "the start of an operation to free Tal Afar".
"I am saying to Daesh that there's no choice other than to leave or be killed," he said, using an alternative acronym for IS.
"We have won all our battles, and Daesh have always lost," he said, telling his troops: "The entire world is with you."
Once a key IS supply hub between Mosul and the Syrian border, Tal Afar is the last major population centre in northern Iraq under jihadist control.
Several hours after the start of the battle, the federal police said it had retaken the village of Al-Abra al-Sghira west of Tal Afar.
The US-led coalition fighting IS in Iraq and Syria welcomed the start of the battle for Tal Afar and pledged support to Iraqi forces involved.
The "operation to liberate Tal Afar is another important fight that must be won to ensure the country and its citizens are finally free of ISIS," the head of the anti-IS coalition said in a statement, using another acronym for IS.
"The coalition is strong, and fully committed to supporting our Iraqi partners until ISIS is defeated and the Iraqi people are free," Lieutenant General Stephen Townsend said.
The coalition would continue to support Iraqi forces with "equipment, training, intelligence, precision fires and combat advice", the statement said.
IS jihadists in June 2014 overran Tal Afar, a Shiite enclave in the predominantly Sunni province of Nineveh, on the road between Mosul and Syria.
At the time, its population of around 200,000 was overwhelmingly Turkmen, one of Iraq's largest ethnic minorities.
Tal Afar's Shiites were directly targeted by IS, while some members of its Sunni minority joined the jihadists and went on to form a contingent with a particularly brutal reputation.
According to the coalition, between 10,000 and 50,000 civilians remain in and around the city.
Authorities have accused the approximately 1,000 jihadists in the city of using civilians as human shields during Iraqi and coalition air strikes earlier this week in preparation for the ground assault.
Abadi said that Iraq's Hashed al-Shaabi paramilitary forces would help army, police and counter-terrorism units to retake Tal Afar.
The umbrella organisation, which is dominated by Iran-backed Shiite militias, has already been fighting to retake a number of other Iraqi cities from IS.
"In the early hours, the guns and flags turned towards their targets," said Hashed spokesman Ahmed al-Assadi.
"Victory is near" in Tal Afar, an "Iraqi city taken hostage and humiliated for years by attacks from these barbarians", he said.
Even before Abadi's announcement, Iraqi planes had dropped leaflets to residents in Tal Afar and its surroundings, the Hashed said in a statement.
The authorities said they had set up a radio station to keep residents informed of developments.
IS overran large areas north and west of Baghdad in 2014, but Iraqi forces have since regained much of the territory.
Once Tal Afar is retaken, Iraqi authorities intend to turn their sights south to retake jihadist-held Hawijah, in the province of Kirkuk, 300 kilometres (185 miles) northwest of Baghdad.
Jihadists also still hold areas in Anbar, a western province that borders Syria and faces major security challenges.
As well as in Iraq, IS has suffered major setbacks in Syria, where US-backed fighters have retaken more than half of its de facto Syrian capital Raqa.
Russia-supported Syrian troops have almost entirely encircled IS in Syria's central desert region, and the jihadists are facing twin assaults from the Lebanese army and Shiite movement Hezbollah on the Lebanon-Syrian border.