Three bombs have exploded in Qamishli in northeast Syria, killing five people and wounding 26 in the city largely controlled by Kurdish fighters.
Two cars and a rigged motorcycle exploded near a cafe and a church, a statement from the region's security forces said on Monday.
The wounded included four security force members, it said, describing the blasts as a "terrorist operation".
With the Kurdish YPG militia at its forefront, the Syrian Democratic Forces (SDF) defeated Islamic State across much of north and east Syria with US help.
A series of bomb attacks have struck towns and villages in northern Syria in the past year, including in the SDF region.
Kurdish leaders say Islamic State sleeper cells still pose a threat and warn that a Turkish offensive at the border would allow a jihadist resurgence.
Australian Associated Press