WASHINGTON — President Trump’s order to withdraw US troops from Syria threatens to cripple US-led efforts to kill and capture ISIS members who continue to launch insurgent-style attacks across its former territory.
The secretive efforts, which involve US troops working with Kurdish and Arab allies, target ISIS members who are hiding among the population in Syria and could resurface to help the group mount a comeback.
Local forces say these efforts have resulted in the deaths and arrests of hundreds of ISIS members — and that many more remain.
The continued threat was underscored Wednesday by a bombing that killed four Americans in Manbij, a Syrian town that was freed from ISIS control more than two years ago. The dead included two US service members, a civilian Defense Department employee, and a Defense Department contractor.
The US has not blamed the attack on ISIS, but the terror organization claimed it was responsible, saying the blast had been a suicide attack. The local militia that partners with the US in Syria said the attack showed the extent to which ISIS remains active.
Former senior US officials who helped to oversee the anti-ISIS campaign say that US-backed operations to decimate ISIS networks in Syria remain critical to defeating it — and that Trump’s decision to pull US troops out will make these operations both more difficult and more dangerous for US troops.
Conducting “raids and other types of special operations on a quick-turn basis” has been central to the US mission in Syria, said Luke Hartig, who worked as a senior counterterrorism official at the Pentagon and on the Obama administration’s National Security Council (NSC) and is now a fellow at New America, a Washington, DC–based research organization.
Hartig said Trump’s withdrawal will make it harder for US troops to carry out operations against ISIS themselves and also to support the partner forces they’ve trained for the job. He added that the US has learned the value of this kind of effort through its long involvement in conflicts in Iraq and Afghanistan.
“We have a lot of experience from 17 years of doing operations that shows that a small number of US forces can greatly enable a larger number of partner forces,” he said. “There’s a lot of value to having us there to enable their operations when they go after targets. The closer you are to the threat, the better the information and intelligence you get.”
Trump has said that the territorial demise of ISIS means US troops are no longer needed in Syria. But US military officials have long warned that it will take more than battlefield wins to deal ISIS a lasting defeat.
The inability of US forces to eliminate al-Qaeda networks in Iraq helped it to reorganize as ISIS after then-president Barack Obama withdrew US forces in 2011. That history factored into the initial outcry from Trump’s Republican allies over his withdrawal order, with Sen. Lindsey Graham calling it “Obama-like.”
After the attack on Wednesday, Graham blamed Trump’s withdrawal decision for emboldening US enemies in Syria. “I saw this in Iraq. And I’m now seeing this in Syria,” he said.
US allies share those concerns. “Some partner countries are worried because of the sheer number of people they had join ISIS and how many remain unaccounted for,” a European military intelligence official said, stressing the need to “put an end to the ISIS threat in the region and in the world.”
The official, who asked to remain anonymous because of the sensitivity of the topic, was recently deployed to Syria, where he joined a small unit of special operations troops from his home country on missions targeting ISIS members. He said that while ISIS has lost most of its former territory in Syria and Iraq, a vigorous counterterrorism campaign is now needed to root out ISIS networks and ensure its defeat. A US withdrawal would make that “impossible,” he said.
“If something doesn’t change fast, we are going to lose control of the area of operations that we needed to maintain to make sure the top leadership and most dangerous foreign fighters who have so far escaped are either hiding in holes or are dead in them,” he said.
Trump has suggested that US troops can continue to carry out operations against ISIS members in Syria from neighboring Iraq, traveling across the border when needed to conduct raids. But while many of the most sensitive operations against senior ISIS members in Syria already are planned and staged from Iraq, according to an Iraqi counterterrorism official, a US withdrawal will hurt the more frequent missions staged from Syria against lower- and mid-level ISIS targets. Those missions are often undertaken by specially trained local forces and supported by US troops.
“Yes, we will be able to continue to operate from northern Iraq, at least for now,” a French counterterrorism official said. “But that isn’t the same as having soldiers living and working alongside the fighters on the ground [in Syria].”
He added: “The coalition will have wasted an excellent chance to leave a counterterrorism operation in place to make sure that the gains of the military campaign are not wasted.”
Former US officials said that even cross-border missions from Iraq into Syria would become more difficult following Trump’s withdrawal.
One former US military official who worked on anti-ISIS efforts from Iraq and Syria said a withdrawal would require US troops to work more with signals intelligence (SIGINT) such as communications intercepts and less with information from human sources (HUMINT).
“You’re relying almost exclusively on SIGINT, because you don’t have a footprint on the ground, whereas now we have a vast amount of HUMINT that we can cull from that helps us delineate the good guys from the bad guys,” he said. “You don’t get the cellphones. You don’t get the pocket material. You’re not going to have the volume of intelligence that provides information to find the next target.”
He added: “Many of those ISIS members who are left are the hardened ones, and they’re mixing in with the local communities.”
“Ideally you would like to have some ability to project power into that environment to do high-value target raids to capture or kill leaders or even mid-level officials from ISIS,” said a former senior Pentagon official who helped to design the campaign against ISIS. “And it just gets a lot more difficult.”
Joshua Geltzer, who was senior director for counterterrorism on Obama’s National Security Council from 2015 to 2017, underlined the added risks elite US troops would face conducting operations in Syria from Iraq.
“Going in and figuring out a way to get out — it’s a difficult way to work,” he said. “Given the riskier nature of going in without a presence there, I would think policymakers would raise the bar for what the mission, if successful, would yield. You’re generally going to want the payout to be pretty high if you put our folks at risk in that sort of way.”
The US did carry out some raids across the Iraqi border before it had a meaningful ground presence in Syria. Geltzer, who is now the founding director of the Institute for Constitutional Advocacy and Protection at Georgetown Law, cited two that are in the public record — a raid targeting a senior ISIS official known as Abu Sayyaf in May 2015 and an attempted hostage rescue the previous year. Neither resulted in US deaths. “But that is a very high-risk way to go about things,” he said. “And everybody who participated in the planning of those operations knew that.”
He added: “Of the thousands of ISIS fighters who remain, some may be in the rank and file, but some presumably are the more capable and more dangerous leadership types. Eliminating those folks is harder, because without a presence in the country you lose insight into what’s going on and you lose the ability to coordinate with partners. Part of what has been remarkable about the counter-ISIS campaign is how much it has relied on partners.”
Nicholas Heras, a Syria specialist at the Center for a New American Security, said a withdrawal would undermine the US partnership with local forces it has spent millions of dollars arming and training, who remain critical to the counterterrorism and counterinsurgency mission now needed in Syria. “You need territory from which to stage operations, and you need local partners that are willing to give you force protection,” he said.
Heras, who has advised the US military on its partner forces in Syria, said it has spent considerable effort on finding and supporting fighters it can trust for sensitive missions. “The main questions you get are: What are your impressions of these guys?" he said. "How good are these guys with Americans? Do we have to worry about getting shot in the back?”
Now the US relationship with those partner forces risks unraveling.
Col. Mohannad Tala worked with US special forces in a parcel of territory near the border with Jordan in southwestern Syria. A rebel against the Bashar al-Assad regime, Tala turned his sights on ISIS when the militants took parts of his home province of Deir ez-Zor in 2013, and the US recruited him to help fight ISIS after ISIS captured large swaths of Iraq in 2014.
“I wanted to fight ISIS before they decided to fight ISIS. So this is why they trusted me,” he recalled in a phone interview from Syria.
He and his men were vetted by the US government and went through a training program run by the US military in Jordan. Then they were sent across the border, to a base in al-Tanf, where they began working with US forces, catching some ISIS members at checkpoints and attacking others holed up around the area.
Over the last two and a half years, he said, they killed dozens of ISIS members on such missions, with US forces often playing a supporting role, and arrested dozens more. The locals they detained were tried in special courts in Syria, Tala said, while the foreigners, some of whom hailed from Europe, were sent to Jordan.
A spokesperson for the US-led coalition declined to discuss the specifics of operations in Syria, saying that the US maintains a “tremendous bond” with its partner forces. “Coalition forces work by, with and through our partner forces on the ground,” US Army Capt. Danielle Covington said in an emailed statement. “We remain focused on an enduring defeat of the remaining elements of ISIS and stabilizing liberated territory to prevent the group’s resurgence.”
Tala, the Syrian commander, lamented the idea of a US pullout. “They cannot fight ISIS if they are not on the ground,” he said. “When the US leaves, ISIS will return, and with more power.”
He added: “We wasted years of work against ISIS in one decision.”
The soldiers at al-Tanf were closed in by pro-Assad forces, limiting them to a small area of operation. The main US partner in Syria, however, the Syrian Democratic Forces (SDF), controls most of the territory ISIS once held, including its onetime capital of Raqqa. The SDF has specially trained counterterrorism units that work with US support to kill and capture ISIS members, and US planners had aimed to help the SDF oversee rebuilding and governance efforts in former ISIS territory, helping to head off a potential ISIS resurgence.
Kino Gabriel, an SDF spokesperson, said that sleeper cells remain a threat across Syria and that the SDF has been working with the US-led coalition to target them. They have killed or captured hundreds of ISIS members away from the front lines in an ongoing effort, he said.
But the Turkish government, to Syria’s north, has long complained about the US partnership with the SDF, which is dominated by an ethnic Kurdish militia linked to separatists waging an insurgency in southeastern Turkey. Turkish President Recep Tayyip Erdogan has repeatedly threatened to attack SDF areas — and it was during a phone call with Erdogan that Trump reportedly made his withdrawal decision. Afterward, Turkey’s defense minister vowed to destroy the SDF after US forces leave. “When the time and place comes, they will be buried in their ditches,” he said.
With the SDF fearing for its survival, US officials have sought to perform damage control, suggesting that the US might strike a deal with Turkey to secure the SDF’s future. Trump threatened this week to “devastate Turkey economically” if it attacks the SDF.
But “the Kurds now know that they cannot rely on us, and our adversaries now have evidence that we are unreliable as well,” said Dana Stroul, a fellow at the Washington Institute for Near East Policy who until recently was a senior staffer on the Senate Foreign Relations Committee. “The damage is done. The SDF will look elsewhere.”
The most likely scenario following a US withdrawal is for the SDF to strike a deal with the Assad regime, which has already retaken much of the country from rebels.
Assad is backed by Russia and Iran, and Iran-backed militia are supporting his forces across Syria, making it unlikely that the US could continue to exert influence in areas that return to government control.
"The Americans are still in Syria now, and if they want to stay, they can stay and support us," Mustafa Bali, the head of the SDF’s media office, said in an interview from Syria. "But if they want to abandon us in this situation and leave Syria, and leave us alone to fight terrorism, exposed to Turkish threats of massacres and genocide, then we may deal with the regime. If we make a deal with the regime, it will be difficult for the Americans to return."
The former senior Pentagon official said that if the Assad government reasserts control over SDF areas, the US may lose the ability to target ISIS members there even with airstrikes.
“If the regime controls the territory then you lose all your legal justification for conducting strikes. The whole legal justification is that the sovereign is unable to control territory,” he said. “The challenge is if the regime says they control all of Syria and they don’t really. Then you have a space on the border of Iraq where shitbirds can pop into the Euphrates River Valley or into Mosul.”