In the darkness of a Mosul safe house in which ten Iraqi soldiers slept, bluish light still emanated from the mobile devices of two intelligence officers busy locating suicide cars, IEDs, and Islamic State (ISIS) bases, and tracking down the names of ISIS members. Providing that information were civilians deep in ISIS territory. On the other side of the battle, the same process was happening in reverse. And those operations were, in many ways, far more sophisticated. Even now that the terrorist organization is disintegrating, its intelligence bureau still presents a major challenge.

THE INFORMATION WAR

For many of the civilians providing information about ISIS to Iraqi authorities, doing so was their way of fighting back against a miserable situation. “So many people in Mosul wanted to cooperate with us because they wanted revenge [against] ISIS for killing their family members,” one Iraqi Army intelligence officer told us. For others, the job was purely for material benefit—the payouts whose size depended on the information provided.

Collecting information was easy enough. One female informant in Mosul did so by flirting with ISIS militants. To keep from attracting attention, she would walk around with her young nieces and nephews since she had no children of her own. Another woman worked as a hairdresser and spied on ISIS leaders through their wives, who often visited her salon.

The hard part of the job was sharing whatever information they gathered. The territories that ISIS controlled were surrounded by Iraqi and allied forces, so it was impossible to pass information in person. There were still Internet cafés in the Islamic State, but in Mosul at least, according to locals, there were “no employees who were not Emni [ISIS Internal Security] informants and no customers who were not ISIS members.” ISIS was also suspicious of sophisticated electronic devices. The very day ISIS took Mosul, it reportedly arrested a civilian on spying charges for wearing a sports watch with GPS.

Although some informants had satellite phones, the most straightforward way to transmit information was through a simple cell phone. But ISIS forbade those, which meant that informants had to get creative about hiding them. The female spy hid hers in her bra; others put them in treetops, in different jars in the kitchen, and in the furniture. One person told us that he buried his phone in the garden, only digging it out once a week to send information.

From there, things only got more challenging: it wasn’t easy to find good cell coverage in Mosul, so informants had to send text messages from elevated places such as the top floors of buildings or neighborhoods on hills. Of course, ISIS members knew that as well, so they searched anyone who went to those areas a little too often. If they found a phone with pertinent messages, that meant execution for the owner. An empty cell phone was even more suspicious. It meant torture.

Despite the dangers involved, informants continued their work and played a crucial role in preparations for the war against ISIS and during major operations, such as the one in Mosul.

An Iraqi soldier stands at the Nabi Yunus shrine in eastern Mosul, April 2017. Muhammad Hamed / Reuters

DATA COLLECTION

As informants risked their lives to get information about ISIS to the Iraqi forces, information was also flowing in the opposite direction: from ISIS sympathizers outside of the group’s territory to ISIS command-and-control. Their information-gathering techniques were relatively sophisticated because they drew not only on the experience of Iraqis who worked for the Saddam Hussein regime’s intelligence services, but also on that of foreign fighters from different countries.

In preparation for taking control of major Iraqi towns, ISIS would start collecting information by penetrating different government institutions there. Locals knew as much, but were afraid to report anything. Although ISIS focused on security institutions, they were also conducting economic espionage. Before taking Mosul, they placed people in Mosul Museum, which they eventually looted. According to museum director Raya Unus, before ISIS took control of the town, the museum got a suspicious new laborer who was likely collecting information on where the most expensive artifacts were stored.

After ISIS took control of major territory, they turned to collecting intelligence on Iraqi-controlled areas. Local taxi drivers were particularly useful in this regard, especially when it was still possible to travel freely between ISIS-controlled territory and the rest of Iraq. Many of the drivers were later arrested. Moreover, in 2015, managers at several Baghdad hotels were arrested for cooperating with ISIS. And in 2016, a schoolteacher in Kurdistan was arrested for not only providing information to ISIS, but also for buying them phone credits so they could receive the information.

At the same time, ISIS would spy on civilians in its own territory. For example, the group employed children to listen to conversations on the streets, in the market, and even in traffic. The adults would frequent other public places. “I used to go to the barbershops in town and listen while waiting in line,” said one member of ISIS intelligence. “I went to the mosques after prayers and listened to what people were talking about while I pretended to be reading the Koran.”

INTELLIGENCE AND COUNTERINTELLIGENCE

At some point, ISIS appears to have penetrated enemy forces. Some members of Kurdish intelligence suspected that some members of the Peshmerga were sympathetic to ISIS and were passing information to the group. According to Halgurd Hikmat, spokesperson of KRG’s Ministry of Peshmerga, “by now we did not find ISIS members in Peshmerga, but I am not saying it is impossible.” In Syria, ISIS had spies in other non-state-armed groups. As recently as two months ago, a foreign fighter who belonged to Hayat Tahrir al Sham (formerly al Nusra) was identified as an ISIS informant.

In turn, ISIS developed a sophisticated counterintelligence operation that focused on catching individuals spying from within. The perceived need for such an operation was understandable. When Iraqi forces started taking back territory, many low- and mid-level local ISIS members started considering cooperating with the Iraqi government to save their lives. With time, ISIS also became more concerned about being penetrated by foreign intelligence agencies. Not only did coalition airstrikes target ISIS leaders with precision, foreign leaders openly talked about infiltrating ISIS. As Chechen leader Ramzan Kadyrov remarked, “even before ISIS became known as ISIS, we had our agents there.”

In charge of rooting out traitors was ISIS’ internal security force, Emni, which drew in some of ISIS’ most experienced and dedicated members and had the strictest vetting process. For example, it was normal for fighters in Syria to change groups multiple times, but Emni only took people who had never fought for any group besides ISIS. In addition to rank-and-file Emni members, ISIS employed an army of informants who worked under cover and could receive $5,000 for each spy caught. Not only was the pay high (an average salary for an ISIS fighter was between $100 and $250 per month), but being an informant was also a good way to jump-start a career. One nearly illiterate individual started as an informant in his village outside of Mosul and was later able to get a job in an ISIS court of appeals in Mosul. Some civilians worked as Emni informants because it helped their businesses. In theory, anyone could have started a business under ISIS, but in practice, an individual would need to be trusted by the organization. And this trust could be gained by providing ISIS with information.

Because ISIS was so afraid of being penetrated at the organizational level, it constantly used undercover informants to monitor its own members. For foreign fighters, such surveillance usually started even before a fighter came to Syria. First, ISIS informants among group supporters in foreign communities checked potential fighters. Then, they were constantly monitored after arriving in Turkey. For example, a prospective fighter from Kazakhstan filmed himself crossing into Syria from Turkey. A smuggler noticed it, and he was immediately arrested by Emni, imprisoned, and later executed—all before he actually even joined the group. ISIS suspected that he was filming the crossing to send his coordinates to a foreign government. Inside ISIS, “everyone was in a constant state of fear of being spied on,” remembered one ex-foreign fighter. According to him, it was impossible to discuss anything, even with co-ethnic friends in their unit, because Emni informants recorded conversations.

Women shop in Mosul, August 2017. Thaier Al Sudani / Reuters

When suspected spies were arrested, ISIS sent them to an internal security prison. There, they were often housed in individual cells without ventilation. Even prison guards were not allowed to talk to them. According to fellow prisoners, suspected spies were tortured so badly that they were not able to walk (their legs were too swollen) or eat (they could not move their hands to grab food). Any females were housed in special women’s prisons and interrogated by female Emni members.

The majority of suspected spies were executed, but sometime locals would be acquitted and let free. According to one ex-ISIS foreign fighter (and later ISIS prisoner), an alleged spy who did not have any serious evidence against him could bribe Emni to expedite the process, and some locals could use connections to get them out. One civilian was imprisoned on spying charges but later freed. He said, “I got out only because one of my relatives had a high position in the organization. He helped me, but later regretted doing so because it cost him promotion.” For foreigners accused of spying, the situation was more serious. An ISIS member who was imprisoned with people who were later executed as FSB spies said that "one of them, half Kazakh, half Kabardin, was a long term friend of a senior Russian-speaking Emni member also from Kabardiano Balkaria. But even that did not help."

Executions of local prisoners usually took place in public as a warning. Foreign fighters were often made to confess their guilt on video before execution. These videos were then distributed for international consumption. It was a common knowledge in prison that after confession, one would be executed, so many foreigners refused to do so, trying to gain time.

To be sure, all of this was controversial even inside ISIS, and some fighters refused to cooperate with Emni on ethical grounds. The force apparently tried at times to recruit senior leaders’ bodyguards, but many refused to spy on the people they were supposed to protect. Some regular fighters were more vocal in their opposition, and there were cases of attacks on Emni informants. For example, one Tunisian foreign fighter suspected that his taxi driver was a member of Emni because, despite wearing civilian clothes, he had a pistol and a hand grenade in the car. The fighter stabbed him with a knife. Indeed, there were hundreds of people in prison for attacking members of Emni.

With time, such confrontations escalated and some ISIS units even attacked Emni prisons. For example, in 2015, when Emni arrested a 16-year-old girl from Kazakhstan, her father, who was in an ISIS assault unit, took around ten fighters with heavy weapons to the prison to demand the release of his daughter. Emni prison guards, afraid for their lives, let her go. Later, all those who participated in the attack were either arrested or disappeared.

Although such sophisticated internal surveillance protected the group, it also increased distrust in the organization and its leadership, which led to internal conflicts and ISIS’ eventual downfall.

NOT YET OVER

In Iraq, the war of weapons is over, but the war of information is not. First of all, many of the most experienced and dedicated Emni members were able to escape when ISIS fell. Compared to ISIS fighters, they enjoyed relative freedom of movement, so when the Iraqi operation in Mosul started, many agents moved to liberated territories, from which they updated ISIS on the movement of Iraqi forces. Even now, their presence is no secret to local civilians. At first, males in liberated areas even refused to shave their beards, still afraid that ISIS Emni who stayed behind would take note of people who violated ISIS grooming policies. According to one senior Emni member currently in hiding, there are around 1,500 ISIS members stationed in Mosul and ready to take up weapons.

It is unclear, however, whether ISIS will be able to penetrate local law enforcement institutions once again. Iraq’s Tribal Mobilization Force (TMF), which is made up mostly of local Sunni groups, replaced its non-local Shia counterparts (the PMUs) and is in charge of security in many areas. Although TMF officers are more trusted by locals than the PMUs, some civilians (and other armed groups) worry that the TMF is already infiltrated by ISIS. And those concerns might be valid. During pre-deployment training last year, the TMF identified and arrested an ISIS mole. According to Faisal Jabar, a leader of one of the TMF groups stationed in West Mosul, “Those dangers are very real, but we are doing our best to reduce them. For example, in order to join our group, a person needs to not have been under ISIS in Mosul, have recommendations from community, and we check his name with security institutions both in Kurdistan and Baghdad.” But not all groups are as meticulous, especially where qualified candidates are hard to find.

Solving the ISIS intelligence problem requires Iraqi forces to win the trust of the local population and increase intelligence cooperation between different armed groups and countries. It will make is easier to catch an ISIS informant if armed groups stationed in the same city share intelligence. And this is not only a problem in Iraq. Emni foreigners (and in particular, its leadership) were among the most likely to escape Iraq and Syria and head elsewhere—including to Europe. Some still work for Emni and, as a result, can simply pick up ISIS activities in a new place.