It was another hot summer night. Sweat trickled from under the helmets of the Rangers creeping through the back streets of Mosul. They had left their Stryker vehicles almost two kilometers behind them so as to not alert their target as they approached his home. Parking so far away entailed significant risk. If the Rangers took fire en route to their objective, they wouldn’t be able to reply with the Strykers’ machine guns, nor quickly evacuate any casualties on the vehicles. But the target that night was worth the risk. Although the coalition referred to Abu Khalaf as al-Qaeda in Iraq’s emir of Mosul, he was really the organization’s number two, second only to Abu Ayyub al-Masri, the Egyptian who had taken charge after the death of Abu Musab al-Zarqawi.

The same military organization responsible for Zarqawi’s demise was now on the trail of Abu Khalaf. That organization was the Joint Special Operations Command, which controlled the military’s most elite units—Delta Force, SEAL Team 6 and the 75th Ranger Regiment, among others—and combined them in a task force in Iraq with the mission to crush al-Qaeda in Iraq. For years the task force had hunted Abu Khalaf without success.

Today, June 24, 2008, it had located him and was striking before he had a chance to slip away. This was the most important mission in which almost any of the Rangers had participated, and it exemplified the machine that JSOC had become. Two files approached Abu Khalaf’s house from the rear. As they moved through the streets, one of two small civilian-style aircraft overhead “sparkled” the objective, briefly illuminating it with an infrared light that looked like a spotlight in the Rangers’ night vision goggles, but was invisible to the naked eye. If any insurgents ran from the building and somehow escaped the Rangers’ cordon, one of the aircraft would track them with a pulsating infrared spotlight so that they could be dealt with after the initial assault.

Tonight’s mission was a platoon mission. One of the platoons had stayed to guard the vehicles. The other three squads of eight men each moved to the objective, hugging walls and staying in the shadows. One squad would take the lead in the assault, breaching and entering the house with the platoon sergeant, the unit’s most experienced soldier. Another stayed in reserve to the front of the objective. The remaining squad split into two teams of four, each taking position on a corner of the block.

Less than 10 minutes after leaving the vehicles, the Rangers were a block from the objective. The four-man sniper/observer team and the isolation squad split off. The rest of the assault force paused at the corner, out of sight of the house. The entire assault force was itching to move. Every second they waited increased the chance of compromise. But the platoon leader wanted to wait until the sniper/observer team was in position on a roof adjacent to the objective. The team’s role was to ensure that the Rangers had “as many eyes and muzzles over all the apertures of the house as possible,” said a Ranger on the mission.

The four Rangers on the team were moving as fast as they could, shimmying from one flat rooftop to another across a 30-foot-long graphite ladder. After examining pictures of the neighborhood, the team leader had picked a site his men could reach without being seen. But they had to cross seven rooftops to get to it.

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The assault force knelt and waited. The tension mounted. The Rangers were kitty-corner from the home of the most powerful insurgent leader in northern Iraq, out of direct line-of-sight of the objective but bathed in streetlights. Finally, the team leader called to say that his team was in position. The trip across the rooftops had taken all of nine minutes, a pace that was “unbelievable, when you think about what’s involved, moving four guys across one ladder,” said the Ranger. “But…it feels like it’s an eternity when you’re sitting on a fairly well-lit street corner at 11 p.m. in one of the most hostile cities in Iraq.”

Abu Khalaf’s compound was defended by a high wall and heavy steel gate. His thick front door provided further protection. The Rangers would need to breach each simultaneously. The assault squad leader scampered up a ladder, dropped down into the compound, and moved quickly to place an explosive charge on the door. The others readied the charge on the gate or climbed ladders to cover him as he set the door charge.

Whispering into a microphone on his shoulder, the sniper team leader reported that two “military-age males” had been lying on the roof of the objective, but one had just stood up. The platoon leader checked a screen slung over his chest that enabled him to watch real-time video from the aircraft overhead. He too saw the man moving on the rooftop. The platoon sergeant’s voice came over the radio: “Three, two, one, breach.”

A blur of movement and violence ensued.

Grabbing a pistol, the man standing on the roof took a couple of steps toward the building’s front. The sniper team leader fired two rounds into his skull, killing him instantly as the breaching charges exploded. The other guard on the roof reached for an assault rifle. Below, the Rangers rushed through the door, which opened into the living room. “Good breach,” said the platoon sergeant into his mike. “Eagles moving in. Foothold.”

When “clearing” a building, Rangers flow through the structure like water, scanning each room in a synchronized choreography. Only if they find any military-age men do the Rangers pause momentarily to leave a couple of soldiers to watch that room.

It was not unusual for the Rangers to clear a compound in less than twenty seconds. The living room opened to a hallway that led to a corridor with several bedrooms. In the first, the squad leader and a young Ranger found a man and woman sleeping on mats. Using memorized Arabic, the squad leader, who was a battle-hardened staff sergeant, and the other soldier—a twenty-one-year-old specialist armed with a light machine gun—told the couple to put their hands up. Neither did. The two Rangers repeated the order. But instead of putting his hands above his head, the man made as if to reach inside his robe. The squad leader’s finger tightened on the trigger of his M4 assault rifle. He had less than a second to make a life-or-death decision.

JSOC’s approach to countering the insurgency

By 2008, JSOC’s successes elsewhere in Iraq had caused the command’s main effort to shift to the country’s north, where its principle strike forces were two Ranger platoons and a small Delta Force element. In the first half of the year, the JSOC task force subjected al-Qaeda in Iraq’s forces to an unrelenting campaign in the north targeting its foreign fighters, its financial and spiritual emirs, and its military leaders. A strike force would hit a house based on signals intelligence that it contained a cell phone linked to an insurgent leader. Once the strike force found the phone, analysts would load its contents into computers packed with advanced network-mapping software, and combine what they found with what had been learned from questioning detainees.

“The analysts would then push out a bunch of additional targets immediately, so we could then destroy that whole cell in one period of darkness,” said a task force source. “That wasn’t happening in 2004 and 2005.”

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Abu Khalaf was the task force’s highest priority target in the north, but its analysts had never been able to link a cell phone to him. “He didn’t even have couriers that were allowed to use phones,” the source said. The keys to finally running Abu Khalaf to ground were National Security Agency cyber sleuths and the task force’s “Mohawks,” Kurdish spies being run by Delta. Suspecting that insurgent leaders were communicating by sharing an email account and writing draft emails that they never sent, but which their colleagues could read so long as they had the right username and password, the NSA had built a query that alerted it whenever the same username and password information were entered in different countries—such as Pakistan, Syria, and Iraq—within the span of a few hours.

From this, the NSA got username and password information for those accounts, allowing the Mohawks to upload software onto computers in Mosul’s Internet cafés that would alert them whenever someone typed in one of these username and password combinations. Analysts soon knew that they were tracking a senior al-Qaeda in Iraq leader from the contents of one of the accounts, but they didn’t know his identity. Finally, someone with that username stayed logged on at a Mosul café long enough for the task force to get a Mohawk there and positively identify him as Abu Khalaf as he walked out and strolled through an adjacent market.

Trailed by the Mohawk and a task force aircraft, the terrorist went back to his house, which became Objective Crescent Lake, simply because Crescent Lake was the task force’s code name for Abu Khalaf. It was now mid-afternoon. The instinct of JSOC’s commander in the north, Ranger Colonel Michael “Erik” Kurilla was to assault the house immediately. But his operations officer persuaded him to keep the house under observation and map out Abu Khalaf’s network by having aircraft follow whoever left the house. There was risk in this: One of those people could be Abu Khalaf, and the task force might lose him.

The task force quickly got two drones over the house. This was routine for JSOC forces in Mosul, who were used to controlling as many as 14 surveillance aircraft over the city at one time. Sure enough, early that evening, Abu Khalaf left his home and returned to the market, where a black sedan picked him up. Kurilla was getting anxious. Even with the task force’s exquisite surveillance assets, it was easy to lose a target as his car weaved in and out of traffic, or as he switched vehicles. But the highly trained imagery analysts kept their eyes on the car as it took Abu Khalaf back to his neighborhood, where he met with two men in the courtyard of a house before returning home.

The task force put a plan together for two simultaneous assaults that night. One platoon would take down Abu Khalaf’s home, the other would target the compound he had just left. The Rangers loaded onto the Strykers and rolled out of the gate.

Completing the assault

The squad leader made his decision. He pulled the trigger, shooting the man in the head. The specialist did the same, firing a burst with his machine gun. Reporting the room “clear and secure,” the squad leader left the specialist to guard the woman. Above them, the sniper team leader shot and killed the second gunman on the roof. But as soon as the squad leader had left the room, the woman dove toward the body of her husband. Again the specialist had to make a split-second decision. Again his instinct told him to pull the trigger. He fired a short burst and the woman’s head split apart.

With the squad momentarily distracted by the firing, a figure darted from the last room left to be cleared and ran up the stairs clutching a pistol. He burst out of the cupola, only for the sniper team leader to put two bullets in his head. The gunman’s lifeless body toppled back through the cupola and fell to the ground floor, crashing into a Ranger, the impact tearing the latter’s night vision goggles from his face.

Abu Khalaf was dead.

The Rangers had been in the house for less than 30 seconds.

With the compound finally cleared, the Rangers began the exploitation phase of the mission. An examination of the dead man in the first bedroom revealed a suicide vest. Honed in nine combat deployments, the squad leader’s instinct had saved numerous lives, as had the specialist’s decision to open fire on the woman. She was the first woman that platoon had shot in about 200 missions.

The Rangers also found about $120,000 in U.S. currency that Abu Khalaf had received from the man he met earlier that day—an Egyptian doctor who, the task force learned via signals intelligence, was in Iraq to work on some type of chemical attack. (Al-Qaeda in Iraq had been trying to mount a chemical car bomb attack on a coalition base for months.) The assault’s impact could be gauged from message traffic the task force intercepted over the next few weeks. “I’m tired of running,” said one AQI fighter. “I have no place to sleep. They hunt me every day. I can’t keep doing this.”

In conjunction with operations by conventional U.S. and Iraqi forces, JSOC’s campaign around Mosul resulted in a two-thirds drop in car bomb attacks from March to June of 2008, from 234 to 78. For suicide car bombs, the drop was 59 percent, from 27 to 11. From a total of 18 JSOC missions across all of Iraq in August 2004, in the spring of 2008, a single Ranger platoon in Mosul averaged more than 60 raids a month.

But JSOC’s—and the U.S. military’s—priority was shifting to Afghanistan. In Iraq, JSOC kept up the pressure, but with fewer forces and more political constraints. The task force was now working closely with Iraqi commandos, a recognition that even the “black” special operations war was taking on more of a local flavor.

For the final three years of the United States’ war in Iraq, JSOC, like all U.S. military forces, was subject to the status of forces agreement between the U.S. and Iraqi governments.

The agreement’s requirement that JSOC obtain warrants for most targeted individuals before launching raids, and the Iraqi government’s habit of releasing most terrorist suspects detained by JSOC, created intense frustration at all levels of the command’s forces in Iraq. The situation regarding JSOC’s targeting of Shi’ite militias and their Quds Force benefactors remained even more tenuous. Quds Force operatives were on an Iraqi government “restricted-target list,” meaning JSOC could not detain them without a warrant from Maliki’s government, which rarely, if ever, provided one.

By early 2010, most of the task force had shifted to Afghanistan. But the units that remained had one more major success to come. On April 18, a combined raid with Iraqi special operations forces killed Masri and three other insurgents in a safe house on the border between Anbar and Salahuddin provinces.

That mission aside, for JSOC, no less than the rest of the U.S. forces, the 2011 withdrawal marked an anticlimactic end to its war in Iraq. Senior U.S. military leaders had always argued that JSOC’s campaign was designed to hold the terrorists and insurgents at arm’s length, to keep them on the back foot, to allow time for a political solution. There can be no doubt that the JSOC task force in Iraq achieved extraordinary successes against al-Qaeda in Iraq and its allies. But absent a holistic political solution in Iraq, and given the reality that the U.S. military presence was destined to end, those gains were always likely to be temporary, and so it proved. The remnants of al-Qaeda in Iraq morphed into the Islamic State, which in June 2014, six years after JSOC killed Abu Khalaf, seized Mosul as part of its lightning sweep across northern Iraq.

More than a year later, it still holds the city.

Read the rest in “Relentless Strike” today.