TEHRAN (Press Shia Agency) – The Iraqi army launched an offensive Sunday aimed at wresting Mosul from the hands of Daesh and ending its brutal two-year occupation.

"The time has come for the greatest victory," Iraqi Prime Minister Haider al-Abadi announced late Sunday on state TV. "I announce the start of Liberating Mosul Operation, by the will of Iraqis, and after depending on Allah."

Al-Abadi said that Daesh would be "punished" for its crimes and that the province's cities and villages will be rebuilt.

"We will rebuild what those criminals have destroyed," he said. "We will bring life back to Mosul and all other areas around Mosul."

In a statement, US Secretary of Defense Ash Carter called the offensive a "decisive moment in the campaign to deliver [Daesh] a lasting defeat."

Though the operation began Sunday, its plans had been known long before.

Earlier Sunday, Hadi Al-Ameri, commander of the Badr organization; Ahmed Al-Asadi, a spokesman for the Popular Mobilization Forces and Gen. Shaker Jawdat, commander of the federal police, arrived at the military base in Qayyarah, a senior security official said, NBC News reported.

Iraq's air force dropped leaflets warning Mosul residents that the liberators are coming, and the Baghdad government directed broadcasts directly into the heart of the occupied city.

Meanwhile, Iraqi forces have circled the country's second-largest city and cut off any supply — or escape — routes that the Daesh fighters holed-up in Mosul could use.

The army is following in the footsteps of Alexander the Great, the Persians, the Turks, the British and other conquerors who have fought over this ancient and strategic city on the Tigris River.

Mosul's location — and the fact that it's in Iraq's oil producing region — is the reason Daesh is so determined to hang onto the city.

Seizing Mosul will not be easy for the Iraqi forces, who are preparing for guerrilla warfare against an enemy that has no problem using civilians as cover.

In addition, the fate of the thousands of Yazidi women who Daesh fighters have taken as sex slaves and are believed to be holding in Mosul is one of the biggest unknowns.