Civilians and security forces in east Mosul fear that Isil sleeper cells may be preparing surprise attacks on liberated neighbourhoods.
Iraqi officials announced the liberation of the eastern half of Mosul last month, three months after launching an operation to retake the city from Islamic State of Iraq and the Levant (Isil).
But the group continues to carry out attacks in districts near the eastern bank of the Tigris river, and security forces backed by local militia groups are sweeping the city amid rumours that Isil sympathisers are moving between neighbourhoods to avoid detection.
"Our problem is the 'displaced' people,” said Hareth, a resident of north-eastern Al Araby district. "We don't know where they are from but they have moved into three houses on our street. We want them to go but we don't have any authority.”
The night before coalition airstrikes had targeted boatloads of Isil fighters attempting to cross the river to infiltrate the neighbourhood.
Nearby, soldiers from the Iraqi army 16th division remained cagey and suspicious. An Isil-dug tunnel exited a hillside near their base in a requisitioned home. "We haven't been down there,” one soldier said. "We will move positions soon, it's not our role to police.”
In a district further south, the role of policing has been handed over to a local militia. "People think that the army are not serious about clearing the city,” said Faisal Jeber, the leader of Mosul's Gallant Force.
A small local militia which patrols several districts, Mr Jeber's force was gathering intelligence on Isil sympathisers.
When Iraqi Security Forces (ISF) had liberated the area, they checked names against a database of suspects but Jeber believed that many sympathisers escaped detection.
"People are doing their intelligence now on new people because ISIS supporters are changing neighbourhoods,” he said, using another acronym for Isil. "This is the main task for the tribal mobilization militias in Nineveh [province].”
Recently his fighters discovered a newly excavated concealed hole in the yard of an abandoned house, which Mr Jeber believed was intended to hide weapons. "We are expecting to find a lot of these holes,” he said.
Earlier this week local media reported the appearance of graffiti in east Mosul threatening that Isil would return, prompting fears of surprise attacks.
Isil launched such an attack in the contested city of Kirkuk on October 21 last year.
The attackers killed over 100 civilians and security forces personnel, diverting attention and forces away from the Mosul operation which had launched days earlier. Security officials had long warned of Isil sleeper cells operating in the city, which has a large Sunni Arab population but has been under Kurdish control since June 2014.
Preventing similar attacks in Mosul will now be a major task for Iraqi authorities. "I can't imagine the efforts that will be necessary to clean the community,” said Mr Jeber. "But we will try to be forgiving and have a new start, otherwise we will be like Isil.”
Meanwhile the ISF are preparing to launch a renewed offensive to retake west Mosul – the last major urban centre under Isil control in Iraq.