Troops board a plane at Spangdahlem Air Base, Germany, on April 7, 2016, on their way to participate in Operation Inherent Resolve.
Two US service members were killed and five were injured Sunday during combat operations in northern Iraq, according to a statement from US Central Command.
The cause of the casualties has not been released by authorities but "initial reports indicate the incident was not due to enemy contact", the DoD said, adding that the incident is under investigation. Two more US servicemembers have died in support of the operation.
The US Special Envoy for the anti-IS coalition, Brett McGurk, expressed his sorrow for the loss of the two unidentified soldiers.More news: CIA director: 'No intelligence' to suggest United States on cusp of nuclear war
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IS claimed responsibility for the deaths of the two soldiers, saying in an online statement that their fighters fired Grad rockets on American troops east of Tal Afar, a town west of Mosul still under the militant's control.
Lt. Gen. Stephen Townsend, the administrator of USA strengths doing combating the Islamic State aggregate in Iraq, said the coalition "sends our most profound sympathies to these legends' families, companions and partners".
As of June, there were now around 6,100 USA military personnel on the ground in Iraq as part of the multinational campaign to eliminate ISIS, according to the Department of Defense.