The U.S. military declared two missing Navy SEALs dead on Sunday after a 10-day search in the Arabian Sea for the pair who disappeared while boarding a ship to confiscate Iranian-made weapons.

“We regret to announce that after a 10-day exhaustive search, our two missing U.S. Navy SEALs have not been located and their status has been changed to deceased,” U.S. Central Command said in a statement. “The search and rescue operation for the two Navy SEALs reported missing during the boarding of an illicit dhow carrying Iranian advanced conventional weapons Jan. 11 concluded, and we are now conducting recovery operations.”

Their names were not released as their families were still being notified.

The search spanned more than 21,000 square miles of ocean, with vessels and aircraft from the U.S., Japan and Spain surveying from the air and the water. They were assisted by Fleet Numerical Meteorology and Oceanography Center, the U.S. Coast Guard Atlantic Area Command, University of San Diego–Scripts Institute of Oceanography, and the Office of Naval Research–Oceanographic Support, Central Command said.