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U.S. Secretary of Defense Lloyd Austin speaks during a press conference at the Pentagon last week.

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Alex Wong/Getty Images

U.S. Secretary of Defense Lloyd Austin speaks during a press conference at the Pentagon last week.

Alex Wong/Getty Images

The U.S. is retaliating after a drone strike killed a U.S. contractor, injured five American service members and wounded one other contractor in Syria, Defense Department said on Friday.

U.S. Central Command conducted airstrikes on targets it believed were connected with Iran’s Revolutionary Guard Corps, Defense Secretary Lloyd Austin said in a statement. Intelligence sources found the drone was of Iranian origin, Austin said.

Videos shared on social media showed explosions in Deir el-Zour, a Syrian province near the Iraq border.

“As President Biden has made clear, we will take all necessary measures to defend our people and will always respond at a time and place of our choosing,” Austin said in the statement. “No group will strike our troops with impunity.”

The drone strike occurred on a Syrian coalition base Thursday and followed recent Iranian attacks against coalition forces, the Pentagon said.

Two wounded service members were treated on site, while the additional victims were medically evacuated to medical facilities in Iraq.

This is a developing story. Check back for updates.

NPR’s Peter Kenyon contributing reporting.