An American serviceman has been killed in Iraq, US defence secretary Ash Carter said, describing it as a "combat death".
The defence secretary, who spoke to reporters in Stuttgart, Germany, where he has been consulting with European allies this week on fighting the Islamic State group, provided no other details.
It was not immediately clear when the serviceman died but Pentagon Press Secretary Peter Cook said he was killed near Mosul, Iraq's second-largest city that has been in the hands of IS militants since they overran large swaths of northern and western Iraq in the summer of 2014.
"A Coalition service member was killed in northern Iraq as a result of enemy fire," the US Central Command, (CENTCOM), said in a statement.
"Further information will be released as appropriate." The statement noted the military's the policy "to defer casualty identification procedures to the relevant national authorities."
Meanwhile, a US military official in Iraq said the American was killed while performing his duty as an adviser to the Kurdish peshmerga troops.
The soldier was killed by "direct fire" after Islamic State forces penetrated the peshmerga forces' forward line, the official said.
The American was two to three miles behind that front line, the official added.
Vice President Joe Biden visited Baghdad last week to exhort leaders of the government in Iraq to resolve internal political strife and concentrate on the effort to defeat the Islamic State group.
Mr Carter, likewise, visited Baghdad recently. The Obama administration has been pressing the effort against IS, which has been slowed down in its quest to overrun Iraq.
Mr Carter presided earlier at a ceremony installing a new commander of US European Command, Army General Curtis Scaparrotti.
This is the third death of a US service member since the US-led coalition's operation against the Islamic State group began in the Summer of 2014.
The last killing of a US service member in Iraq was in March, when a US Marine stationed at Makhmour base outside the IS-held city of Mosul was killed by an IS rocket attack.
The first US service member killed in Iraq was a special operations solider killed in a firefight in October 2015 during a raid on an Islamic State group prison.