Deadly Drone Attack in Syria Prompts US Retaliatory Airstrike.

The main air defense system at a coalition military base in northeast Syria was "not fully operational" when a suspected Iranian drone hit the installation on Thursday, killing a U.S. contractor and injuring six other Americans. The circumstances are under investigation, military officials said. The United States retaliated by launching airstrikes against militant sites linked to Iran's Islamic Revolutionary Guards Corps. The attacks are likely to stoke tensions with Iran, which Biden administration officials call the largest security threat in the Middle East.