DAESH terrorists killed a US Navy SEAL in northern Iraq on Tuesday after blasting through but failing to overrun a town in the Peshmerga controlled area, officials said.
The dead man was the third American to be killed in direct combat since the launch of the 2014 US campaign to degrade and destroy the terrorist group.
"It is a combat death, of course, and a very sad loss," US Defence Secretary Ash Carter told reporters during a trip to Germany.
A US defence official announced that the deceased man was a Navy SEAL. The SEALs are considered to be among the most able of US special operations forces and capable of taking on dangerous missions.
A senior official within the Peshmerga forces facing DAESH in northern Iraq said the man had been killed near the town of Tel Isqof, around 28 kilometres (17 miles) from Mosul.
DAESH occupied the town at dawn but were driven out later in the day by Peshmerga forces. A US military official said the coalition had helped the Peshmerga with air support from F-15 jets and drones.
The official, speaking on condition of anonymity, said the man was killed "by direct fire" from DAESH.
Carter's spokesman, Peter Cook, said the incident took place during a DAESH attack on a Peshmerga position some 3-5 km behind the forward line.
Good terrorist, bad terrorist
In mid-April the US announced plans to send an additional 200 troops to Iraq, and put them closer to the front lines of battle to aid forces in Iraq who are fighting against DAESH.
US troops have frequently assisted the YPG in the past, which is the militant wing of the PYD, in northern Syria since December 2015.
US Defence Chief Ash Carter admitted last week that the PYD and YPG are linked to the outlawed PKK, an armed Marxist-Leninist group listed as a terrorist organisation by Turkey, the US, the EU and NATO.
Eva Savelsberg, chairperson of the Berlin-based European Centre for Kurdish Studies, told TRTWorld that despite the US acknowledging the link between the YPG and the PKK, it is unlikely that the US will cease its support for the group.
Turkey has long expressed its dismay at US support for the PYD, which Ankara considers to be identical to the PKK terrorist group that has carried out a series of attacks on civilians and police in Turkey.
US officials argue that the military gains against DAESH are not enough, while Turkish President Recep Tayyip Erdogan had warned it would be a fatal mistake to play favourites among terrorist groups."
Erdogan accused the US of forming an "imaginary distinction between good terrorists and bad terrorists by employing "double standards on terrorism."
Since the 2003 US invasion, Iraq has been beset by corruption, political imbalance, a growing fiscal crisis and aggrieved public, the perfect bedrock for DAESH to gain a foothold across the nation.