On December 13, a joint US-Syrian patrol was ambushed by a member of Syria’s own security forces near Palmyra, a city in central Syria once controlled by the ISIL (ISIS) group.
Two American soldiers and an interpreter they were shot dead, and four people were wounded, before Syrian forces killed the gunman.
After the attack, US and Syrian officials linked the attacker to ISIL, which once controlled vast swathes of Syria and Iraq, and vowed to retaliate.
The incident highlights the growing cooperation between the United States and Syria against ISIL, particularly after Damascus was united the US-backed coalition against the group in November.
While it remains unclear whether the attacker was a member of ISIL or another group opposed to US-Syrian relations, analysts say cooperation between the two countries is strong and growing.
“The Syrian government is responding very robustly to the fight against ISIL following US requests to do so, and it should be noted that HTS [Hayat Tahrir al-Sham]before he was in government, he had a long-term policy of fighting ISIL,” Rob Geist Pinfold, an international security scholar at King’s College London, told Al Jazeera, referring to former Syrian President Ahmed al-Sharaa’s group.
“It is [HTS] he did it in Idlib, and attacked the rebels and the cells, and this is more a continuation of that policy.”
The spokesman for Syria’s Interior Minister, Noureddine al-Baba, told Syria’s Al-Ikhbariah TV that there was no direct line of command for the gunman within Syria’s internal security forces, and that he was not part of the force tasked with escorting the American forces. Investigations are underway, he added, to determine whether he had direct links to ISIL or adopted a violent ideology.
ISIL attacks
In May 2015, ISIL took over the city of Palmyra from the former Syrian government.
Famous for its Greco-Roman ruins, the city went back and forth between regime forces and ISIL until the group was ousted in 2017.
In May 2017, the US-led coalition also forced the group out of Raqqa, which ISIL had declared the capital of its so-called caliphate three years earlier.
Many surviving ISIL fighters were imprisoned in them al-Hol and Roj camps in northeastern Syria, controlled by the US-backed Syrian Democratic Forces (SDF). Others fled into the Syrian desert around Palmyra, from where attacks occasionally began.
When the regime of former Syrian President Bashar al-Assad fell on December 8, 2024, analysts said that ISIL fighters used the resulting chaos to move into various cities across the country. In June, the group he launched an attack on a church in Damascus that killed at least 25 people.
Samy Akil, a fellow at the Tahrir Institute, said that recent estimates put the ISIL operatives in Iraq and Syria at between 3,000 and 5,000 fighters.
But experts told Al Jazeera that coordination between Damascus and Washington has improved over the past year, pointing to the fact that Syrian security forces have thwarted several ISIL attacks thanks to intelligence provided by the United States.
“The new government of Ahmed al-Sharaa is committed to fighting the group and, in contrast to the Assad era, the al-Sharaa government receives regular advice from US intelligence, and probably other forms of US support as well. That’s a pretty powerful combination,” said Aron Lund, a researcher at Century International, who focuses on Syria.
This collaboration has seen a reduction in ISIL attacks in Syria, according to a report by the consulting firm Karam Shaar Advisory. ISIL launched an average of 63 attacks per month in 2024, while in 2025, that number dropped to 10, according to the report.
“Since HTS arrived in Damascus, collaboration [with the US] it became much easier,” Jerome Drevon, a senior analyst with the International Crisis Group, told Al Jazeera.
Structural defects
After the fall of the Assad regime, there were questions about how security would be enforced. The few thousand HTS members who previously only controlled Idlib in northwestern Syria would not be enough to enforce security across the country.
Syria’s security forces have undertaken a serious recruitment drive, bringing in tens of thousands of new recruits to add to many of the existing former opposition battalions that have been incorporated under the new state security apparatus.
With such a large recruiting campaign, analysts said, verification was a difficult task.
“The Palmyra attack indicates structural flaws rather than a simple one-off event. The integration of fighters of the former factions and rapid new recruitment produced irregular verification and surveillance, aggravated by a permissive environment for radical views, which allows infiltration to persist,” said Nanar Hawash, senior Syria analyst of the International Crisis Group, to Al Jazeera.
“Together, these factors speed up early warning signals and create room for hidden threats, raising the risk of repeated attacks.”
Analysts said they expect Syrian security forces to improve the vetting process over time. Meanwhile, another attack like that of December 13 was possible and could undermine the faith of the United States that the government of al-Sharaa can provide security in Syria.
“It could happen again because of the big numbers [of new recruits]but over time, the government will improve its game and be more careful to prevent this from happening again, because it will have consequences,” said Drevon.
“We should be careful to generalize based on one attack, which may be a one-off. But if it happens again, it may change the perception of the Syrian government.”
What does ISIL want?
As for ISIL, analysts said the group’s priorities have changed since the fall of al-Assad.
“What we are seeing now is ISIL trying to test the boundaries and carry out attacks knowing that it cannot gain territorial control,” said Akil.
“It aims to destabilize and stay relevant.”
“ISIS cannot hold cities or overthrow governments. But it doesn’t have to. Its strength lies in destabilization,” Hawach said. “The Palmyra attack showed that one operative with the right access could kill three US personnel and upset a bilateral relationship.”
Analysts say ISIL could destabilize Syria by targeting state security forces, religious minorities – as it did in the Damascus church attack in June – or any outsider on Syrian soil, from US soldiers to humanitarian or United Nations workers. The group may also seek to capitalize on the tensions between the SDF and Damascus on disagreement on how to integrate first in the state security apparatus.
The SDF also administers al-Hol and Roj prison camps in northeastern Syria, where many of ISIL’s most battle-hardened fighters and commanders are held. This could be a prime target for ISIL in Syria.
“ISIL thrives in those gaps,” Hawach said.
“It is a guerrilla rebellion, not a caliphate, but in a fragile state, this is enough to cause serious damage.”