Iraqi military forces are reportedly moving into position for the long-anticipated offensive to retake the captive city of Ramadi from ISIS, which has responded by threatening to kill Ramadi residents if they raise white flags.

“ISIS threatened the people of Ramadi of death [sic] in the event of raising white flags and heading to the security forces,” said Anbar Council member Rajia Barakat, as related by UPI. “The people of Ramadi are living in a state of fear and panic after being threatened by criminal and terrorist gangs. The organization is besieging hundreds of families inside Ramadi.”

ISIS militants are also said to be preventing residents from fleeing the city ahead of the assault. The total population of the city is estimated at 450,000.

The Iraqi military already reports some success on the outskirts of Ramadi, killing dozens of militants with preliminary rocket barrages, detonating 82 explosives (including five booby-trapped vehicles) and taking out a rocket base with seven Katyusha missiles.

UPI reports Ramadi is now encircled by Iraqi forces after weeks of bloody battles with Islamic State forces in the surrounding area. Armor and artillery are being moved into position for a heavier assault.

Reuters reports that efforts to liberate Ramadi from ISIS have been hampered by “heavy use of improvised explosive devices, inadequate troops and equipment due to government cash shortages, and stringent rules of engagement for U.S.-led air strikes.” It has been six months since promises were made, by both Iraqi and U.S. officials, that Ramadi would be quickly retaken.

However, commanders are optimistic after successful efforts to cut Islamic State supply lines, prevent reinforcements from moving into the city, and seize strategic positions in surrounding downs. One important objective has been seizing control of the Euphrates River, which ISIS has been using to resupply its forces in Ramadi.

Recapturing the city would be an enormous morale boost for Iraqi forces, and a commensurate blow to ISIS. It would also help build momentum for the decisive battle to recapture Mosul in the north, and push the Islamic State out of Iraq completely.

The Army Times reports that U.S. troops from the 82nd Airborne Division have been training Iraqi forces for brutal urban combat. Their training has included marksmanship, medical skills, strategic planning, and special skills such as disarming the Islamic State’s many Improvised Explosive Devices. American officers described their Iraqi charges as “better trained, better equipped, and better led” than the Iraqi forces ISIS routed from Ramadi.

“It may not be moving as quickly as we would like it, but there’s progress,” said Colonel Curtis Buzzard, commander of the 3rd Brigade Combat Team. “This is the Iraqis’ fight to win, enabled by us, but they must own it, and they know it.”