A convoy of black National Security Service pickup trucks race through liberated eastern Mosul, sirens blaring to cut through the busy traffic.
The black vehicles pull up at the edge of an industrial zone and officers jump out, some scattering into defensive positions as others approach a row of abandoned mechanics’ garages.
Behind the corrugated tin of a sliding gate, they find what they are looking for. On a dusty concrete floor lie the tools of ISIL’s insurgency: landmines, C4 explosive and metal ball bearings wrapped tightly in duct tape, oil canisters filled with home-made explosives. Pressure plates used to ignite these improvised explosive devices (IEDs) have been stacked on wooden planks to prevent water damage.
As the campaign to dislodge ISIL from west Mosul gets under way, it is becoming clear that the extremist group’s terror threat has not been banished from the liberated half of the city. Sleeper cells that security officials say proliferated during ISIL’s rule are becoming increasingly active, seeking to disrupt the return to normal life and divert government forces from their battle on the opposite bank of the Tigris river.
On February 10, just two weeks after the government declared eastern Mosul liberated, a suicide bomber attacked the popular My Fair Lady restaurant in the central Zuhour neighbourhood, killing 11 people. On Sunday, hours after the military launched its offensive on west Mosul, two militants blew themselves up in eastern Mosul, killing three soldiers and two civilians.
With Mosul’s security forces severely depleted after more than two years under ISIL rule, the NSS and what remains of the police force are struggling to contain the terror as they rebuild their presence.
The NSS, akin to western intelligence agencies such as the FBI in the US or Britain’s MI5, received a tip-off about the cache in the industrial zone from one of its informants in the city.
As the unit probed deeper into the industrial estate, they found more evidence of ISIL’s threat: piles of mortar rounds in workshop; sacks of phosphate, a component of the explosives used for IEDs, stacked high in a warehouse. Next door was a car bomb factory with a military vehicle left behind by the retreating militants before it could be transformed into a bomb on wheels.
Major Muntathar, who led the raid, said he could not say whether the IEDs were made while ISIL still controlled the area or in secret after Iraqi forces drove the militants out.
Extremist terror has long plagued Mosul, and the number of ISIL supporters there grew after the group took over the city in June 2014.
"There are a lot more cells in Mosul now than before the occupation," said Col Isham Mahmoud of the NSS.
The security agency has deployed about 200 men in Mosul. The police force for Nineveh province, of which Mosul is the capital, has only 6,000 police officers in the city compared with 28,000 before the ISIL takeover, according to the force’s Col Uday Saber.
Security forces fled after ISIL stormed the city. The policemen that did not make it out were captured and brutally murdered, their bodies dumped in mass graves outside the city. One site alone, a sinkhole to the south of the city, is thought to contain the bodies of at least 2,100 policemen, Col Saber said.
A batch of 1,700 newly trained policemen is expected in east Mosul any day now, but rooting out ISIL remains a tough task.
After more than two years of tyrannical rule, the extremist group is deeply unpopular with the majority of Mosul’s residents. The NSS claims that up to 200 calls are made each day to a hotline set up to pass on information on ISIL members or sympathisers remaining in east Mosul. But with resources limited, it will take time to follow up on this flood of information and make arrests.
"It might take six months or more before the east side of Mosul is cleared of sleeper cells," Col Saber said.
A survivor of the My Fair Lady bombing believes the fear of being caught by security forces will only drive the extremists to step up suicide attacks.
"Daesh members hiding in east Mosul know that they will be killed sooner or later. That’s why they do something like this, because they think they will go to heaven if they do," said Mohammed, a son of the restaurant owners, who lost his younger brother and an uncle in the attack.

Source: The National