QUITO — The survivor of a U.S. strike on a submersible vessel accused by the Trump administration of transporting drugs in the Caribbean was released by authorities in Ecuador after prosecutors said they had no evidence he committed a crime in the South American nation, a government official said Monday.

U.S. Navy helicopters were dispatched as part of the search and rescue team after overhead video showed people who seemed to have survived the initial strike.

News of the attack comes amid the sudden announcement of the departure of the top military official overseeing the strikes in the Caribbean on Thursday. Adm. Alvin Holsey announced that he is leaving his role as the head of the U.S. Southern Command, which oversees military operations in Latin America, on December 12.

Trump says the U.S. is blowing up boats carrying deadly fentanyl to the United States. U.S. and other officials say the route under attack carries cocaine and marijuana to Europe and Africa.