An image shared by the U.S. military's Central Command on social media shows items seized from an Iranian boat near the coast of Somalia on Jan. 11, 2024. U.S. MILITARY HANDOUT

Two Navy SEALs who went missing on Jan. 11 while on an interdiction mission are considered dead, the U.S. military said Sunday.

The SEALs were reported missing during a mission near the coast of Somalia to board a ship carrying Iranian weapons, U.S. Central Command said in a statement.

Ships and aircraft from the U.S., Japan and Spain searched more than 21,000 square miles, CENTCOM said, adding that the search for the missing SEALs, who have not yet been publicly identified, has now been changed to a recovery effort.

Defense officials earlier told CBS News that the missing sailors went overboard while attempting to board the Iranian vessel. The SEALs were climbing up a vessel when one got knocked off by high waves in the Arabian Sea, the Associated Press reported. Under their protocol, when one SEAL is overtaken, the next jumps in after them.

"We mourn the loss of our two Naval Special Warfare warriors, and we will forever honor their sacrifice and example," CENTCOM's Gen. Michale Erik Kurilla said. "Our prayers are with the SEALs' families, friends, the U.S. Navy, and the entire Special Operations community during this time."

The U.S. military seized "advanced lethal aid" being sent to supply Houthi rebels in Yemen during the Jan. 11 raid, officials said last week. The initial analysis of the weapons found they were the types being used by the Houthis to attack commercial vessels in the Red Sea.

The U.S. Navy sank the ship after it was deemed unsafe, Central Command said. The ship's 14 crew were detained.

"This was not related to the strikes in Yemen," National Security Council spokesperson John Kirby said about the incident on "Face the Nation" last week. "This was normal interdiction operations that we've been conducting for some time to try to disrupt that flow of weapons supplies to Yemen."

The Houthis have vowed to keep attacking ships they deem connected to Israel or Israel's international allies. Houthi rebels, who control swaths of Yemen, justify the missile and drone launches as retaliation for the ongoing Israeli military operation in Gaza against the Palestinian militant group Hamas.

The Biden administration last week declared Yemen's Houthi rebels to be a "specially designated global terrorist group."

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