BAGHDAD — Nine Iraqi soldiers were killed when U.S.-led coalition warplanes mistakenly struck the troops near the ISIS-controlled city of Fallujah, Iraq’s defense minister said on Saturday.

Khalid al-Obaidy ordered an investigation into Friday’s alleged friendly-fire incident. He said the aircraft were supporting Iraqi forces battling ISIS because poor weather had grounded the country’s helicopters. The victims included one officer, according to al-Obaidy.

Defense Secretary Ash Carter called Iraq’s prime minister, Haider al-Abadi, to express condolences. Carter later told reporters that the incident appeared to be “a mistake that involved both sides.”

The U.S. military said the strikes came in response. . .

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