A US Marine who fell overboard from an attack ship in the Caribbean has become the first known American casualty in the Trump administration’s operation targeting drug-trafficking boats.

Nigerian-born Lance Cpl Chukwuemeka E. Oforah, 21, fell from the USS Iwo Jima on 7 February and was lost at sea. He was pronounced dead after a lengthy search, which ended 10 February.

His death was announced on Wednesday and remains under investigation by the military The Florida native was assisting Operation Southern Spear, which has carried out 38 lethal strikes on alleged drug boats in the Caribbean Sea and Pacific Ocean since September.

It played a key role in the capture of Venezuelan President Nicholas Maduro.

A statement from the US Marines contained no details regarding how he may have fallen from the ship.

“We are all grieving alongside the Oforah family,” said Col Tom Trimble, commanding officer of the Marine Expeditionary Unit known as Special Operations Capable.

“The loss of Lance Cp. Oforah is deeply felt across the entire Navy-Marine Corps team. He will be profoundly missed, and his dedicated service will not be forgotten.”

A news release from the military branch said the sprawling search for Oforah involved five ships and 10 aircraft. The USS Iwo Jima was used to transport Maduro after his capture in a US raid.

Maduro’s capture came after weeks of a military build-up in the region, along with frequent strikes on vessels that the Trump administration said were carrying drugs headed for the US.