The anti-Islamic State campaign claimed its first U.S. casualty when a Marine jumped from a V-22 Osprey into Persian Gulf waters, when the aircraft experienced engine trouble Wednesday as it took off from an amphibious assault ship supporting air strikes in Iraq and Syria.

The Marine, identified as Lance Corporal Jordan Spears, 21, of Memphis, Indiana, is presumed lost at sea after he and another crewman on the tilt-rotor aircraft jumped when it was apparent the plane was going to crash. The pilots regained control of the aircraft and were able to land it back on the USS Makin Island. 

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Rescue units immediately went into action, and recovered the other crewman who is now being treated for injuries. The U.S. Navy called off search operations for Corporal Spears Thursday and declared him lost at sea.

Pentagon spokesman Rear Admiral John Kirby said Spears' unit, the 11th Marine Expeditionary Unit, had been supporting current operations in the Gulf, including the air strikes against the ISIL or ISIS in Iraq and Syria.

"That squadron and that ship were in the Gulf supporting Central Command operations," Kirby said, referring to the major command responsible for U.S. forces in the Middle East . "So there's no question that this Marine's death is related to the operations that are going on in some form or fashion."

Both Navy and Marine Corps investigators are looking into the cause of the mishap. Navy sources said the V-22 lost power after take off and was falling into the sea when the two crewmembers jumped off. The Osprey takes off and lands vertically, but the twin rotors at the end of its wings tilt after takeoff to allow the plane to fly horizontally.

The V-22 is generally used as a personnel and equipment transport aircraft by the U.S. Navy, Marines and the Air Force.