Iraqi warplanes are bombarding the jihadist group Islamic State’s positions in Tal Afar, in preparation for a ground assault on the town.
Tal Afar became the last IS stronghold in northern Iraq in July after the government declared victory in the city of Mosul, 55km (35 miles) to the east.
It is not known when the offensive will begin, but army, police and special forces units are heading to the town.
Thousands of civilians have meanwhile fled the area, according to the UN.
In November 2016, a month after the launch of the Mosul offensive, the Shia-led paramilitary Popular Mobilisation (Hashd al-Shaabi) force took the road to the west of the town and captured an airbase just to the south.
The route was later severed on the eastern side of Tal Afar as troops sought to prevent IS sending reinforcements and supplies to Mosul.
Federal police chief Lt Gen Raed Shakir Jawdat discussed plans to retake the town on Monday, saying armoured and elite units were “regrouping in combat positions”.
Although the bombardment of the town by Iraqi air force and US-led coalition warplanes has intensified in recent days, targeting IS headquarters, tunnels and weapons stores, there are no indications as to when Prime Minister Haider al-Abadi might announce the start of the assault.
However, an unnamed officer overseeing the operation told the Associated Press that troops were not expected to push into Tal Afar for another few weeks.
Last month, a senior Iraqi commander who once served as mayor of Tal Afar said between 1,500 and 2,000 militants and their family members were holed up inside the town.
He described the terrain in Tal Afar as “favourable” to Iraqi forces, noting that only one part of the town had narrow streets comparable to those seen in Mosul’s Old City. Few civilians are believed to be left in Tal Afar, with 49,000 having fled since April.
UN Humanitarian Co-ordinator Lise Grande described the conditions in Tal Afar as “very tough”, with shortages of food and water, and said civilians escaping were having to walk for up to 20 hours to reach safety and assistance.