The soldier was hit by direct ISIS fire on Tuesday about 20 miles (32 km) from Mosul, said Colonel Steve Warren, a spokesman for the US-led coalition fighting ISIS.
“The enemy penetrated the Kurdish lines,” Warren said of the attack. “They went about five kilometers past the forward line of troops with some truck bombs.”
The American troop’s name and rank weren't immediately disclosed in accordance with military protocol.
"It is a combat death, of course. And a very sad loss," US Defense Secretary Ashton Carter said Tuesday in Stuttgart, Germany, where he was meeting NATO allies.
Tuesday's fatality was the second for the US military this year in Iraq. An American Marine was killed and several more were wounded by Daesh rocket fire in northern Iraq in mid-March.
The last US service member to be killed in Iraq prior to the March death was in October 2015.
Daesh terrorists, who were initially trained by the CIA in Jordan in 2012 to destabilize the Syrian government, now control large parts of Iraq and its western neighbor, Syria.
Iraq has on several occasions complained about the ineffectiveness of airstrikes launched by the US and its allies against ISIS.
The militants have been committing brutal crimes against all ethnic and religious communities in Iraq and Syria, including Shias, Sunnis, Kurds, Christians and others.
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