The Pentagon says the five armed assailants captured by U.S. forces after seizing a commercial ship near Yemen over the weekend were likely Somali and not Iranian-backed Houthi rebels.

The USS Carney shot down at least three Houthi drones headed in the ship’s direction in the southern Red Sea on Sunday and responded to a distress call from a civilian commercial vessel that was fired upon by a ballistic missile,

Iran-backed Houthis have stepped up attacks on shipping in the Red Sea after seizing an Israeli-owned vessel last week. The violent incidents have forced global shipping to take stock of potentially rising risks.