The attack came as the United Nations said that fighting with IS in northern Iraq could displace another 30,000 people, adding to millions who have already fled their homes.

And in Baghdad, throngs of Shiite pilgrims braved the threat of bombings by IS, which have killed dozens of people in recent days, to take part in a major annual religious commemoration.

The sailor from the special operations force was the third coalition member killed by enemy fire in Iraq since IS overran swathes of the country in 2014.

Arizona Governor Doug Ducey identified the fallen SEAL as Charlie Keating IV, who attended high school in Phoenix.

President Barack Obama hailed the 2011 withdrawal of American troops from Iraq as a major accomplishment of his presidency, but US forces have been drawn back into combat in the country against IS.

Pentagon spokesman Peter Cook said the death occurred during an IS attack on one of the Kurdish peshmerga forces’ positions north of Iraq’s jihadist-held second city Mosul.

A US defence official said the SEAL’s death was the result of “an orchestrated attack.”

A coalition military official said the American was killed at 9:30 am (0630 GMT) by “direct fire” after “enemy forces penetrated” the peshmerga line.

– Firefight with IS –

The SEAL was a member of a “small team” that was present at a peshmerga encampment behind the original front line during the IS attack, which involved explosives-rigged vehicles, bulldozers and infantry, the official said.

“They fought, but they’re a small number and they’re not supposed to be in direct contact,” and they departed by American helicopter after the SEAL was shot, according to the official.

Kurdish forces are deployed in Nineveh province, whose capital Mosul is IS’s main hub in the country.

IS attacked the peshmerga in multiple areas of northern Iraq on Tuesday in an attempt to “thwart the plan to liberate Mosul”, said Jabbar Yawar, the secretary general of the autonomous Kurdish region’s peshmerga ministry.

Iraq’s Joint Operations Command said IS overran the Tal Asquf area and that the group employed suicide bombers.

Tal Asquf is a small Christian town whose population fled in 2014. According to the Kurdistan Region Security Council, the town was “completely cleared” of IS fighters later Tuesday.

Romeo Hekari, who heads a Christian unit fighting IS under peshmerga command, also said Tal Asquf was back under full control.

The United States announced last month that it was deploying additional forces to Iraq, bringing the official total to more than 4,000.

– Boots on the ground –

The coalition is carrying out daily air strikes against IS, and while most American forces on the ground in Iraq play advisory and support roles, Washington has also deployed special forces to carry out raids against IS, and US Marines to provide artillery support.

Two US military personnel had already been killed by the jihadists in Iraq: an American Marine by rocket fire in March and a special forces soldier who died of wounds received during a raid last October.

Obama repeatedly pledged that there would be no “boots on the ground” to combat IS, but the administration has since sought to define the term as meaning something other than American forces being on the ground and in combat.

“They are wearing boots, and they are on the ground, but that… doesn’t mean that they are in large-scale ground combat,” State Department spokesman John Kirby recently told journalists.

As Kurdish forces and the jihadists clashed on Tuesday, the United Nations expressed concern that “as many as 30,000 newly displaced individuals” could arrive in Makhmur southeast of Mosul, fleeing fighting in the area.

In Baghdad, tens of thousands of pilgrims converged on a shrine to mourn the death of Imam Musa Kadhim, the seventh of 12 imams revered in Shiite Islam, who was killed in 799 AD.

A shrine official said that “millions” had taken part in commemorations in recent days, despite IS-claimed bombings targeting the pilgrims that have killed at least 37 people in the past week.

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