Middle East leaders and their Western allies have been warning that ISIS could exploit the fall of the Assad regime to stage a comeback in Syria and neighbouring Iraq, where the extremist group once imposed a reign of terror over millions.
The militant group has been attempting just that, according to more than 20 sources, including security and political officials from Syria, Iraq, the US and Europe, as well as diplomats in the region.
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The group has started reactivating fighters in both countries, identifying targets, distributing weapons and stepping up recruitment and propaganda efforts, the sources said.
So far, the results of these efforts appear limited.
Security operatives in Syria and Iraq, who have been monitoring ISIS for years, told Reuters they foiled at least a dozen major plots in 2025.
A case in point came in December, the month Syria’s Bashar Assad was toppled.
As rebels were advancing on Damascus, ISIS commanders holed up near Raqqa, former capital of their self-declared caliphate, dispatched two envoys to Iraq, five Iraqi counter-terrorism officials told Reuters.
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The envoys carried verbal instructions to the group’s followers to launch attacks.
But they were captured at a checkpoint while travelling in northern Iraq on December 2, the officials said.
Eleven days later, Iraqi security forces, acting on information from the envoys, tracked a suspected ISIS suicide bomber to a crowded restaurant in the northern town of Daquq using his cell phone, they said.
The forces shot the man dead before he could detonate an explosives belt, they said.
The foiled attack confirmed Iraq’s suspicions about the group, said Colonel Abdul Ameer al-Bayati, of the Iraqi Army’s 8th Division, which is deployed in the area.
“Islamic State elements have begun to reactivate after years of lying low, emboldened by the chaos in Syria,” he said.
Still, the number of attacks claimed by ISIS has dropped since Mr Assad’s fall.
ISIS claimed responsibility for 38 attacks in Syria in the first five months of 2025, putting it on track for a little over 90 claims in 2025, according to data from Site Intelligence Group, which monitors militants’ activities online.
That would be around a third of 2024’s claims, the data shows.
In Iraq, where ISIS originated, the group claimed four attacks in the first five months of 2025, versus 61 total in 2024.
Syria’s government, led by the country’s new Islamist leader, Mr Ahmed al-Sharaa, did not answer questions about ISIS activities.
Defence Minister Murhaf Abu Qasra told Reuters in January the country was developing its intelligence-gathering efforts, and its security services would address any threat.
A US defence official and a spokesperson for Iraq’s prime minister said ISIS remnants in Syria and Iraq have been dramatically weakened, unable to control territory since a US-led coalition and its local partners drove them from their last stronghold in 2019.