On 20 January, three suicide drones targeted al-Tanf, a military base in southeastern Syria hosting US forces.
The attack didn't cause significant losses: the troops there shot down two of the drones, while the third exploded after colliding with a building belonging to an allied Syrian rebel group, US forces said at the time.
Two days later, an unknown armed group called "the Inheritors" claimed responsibility.
Its statement, published by websites linked to Iranian-backed armed factions, was adorned with a green title that read "Islamic Resistance in Iraq - Formation of the Inheritors".
"No one can ever stop our operations," the group said, dating the statement as the same day the operation was carried out.