The US military said Saturday that an American service member died during an operation alongside Iraqi security personnel in Nineveh province.
"One US service member died today during an Iraqi Security Force mission in... Iraq, while advising and accompanying the ISF during a planned operation," US Central Command said in a statement.
Iraqi forces periodically launch operations in the country's west and northwest border areas, targeting Islamic State group sleeper cells, with support from a US-led coalition.
Iraq's government in late 2017 declared victory against IS, which seized vast swathes of the country including the key northern city of Mosul in a lightning 2014 offensive.
But the jihadist group has lately "solidified its insurgent capabilities in Iraq" , according to a report this week by the US Defense Department watchdog.
The report also said IS was "resurging" in neighbouring Syria, despite a Kurdish offensive -- backed by US-led coalition air support -- to seize the last shred of the jihadists' self-styled caliphate in Deir Ezzor province earlier this year.