At least 104 people have died and 20 others remain missing after a U.S. submarine attacked Iran’s frigate IRIS Dena.

Axar.az reports, citing Mehr, the ship, which had 136 crew members on board, was returning from military exercises as part of the Peace Milan 2026 drills.

In addition, 32 crew members were reported injured and are receiving treatment at a hospital in Sri Lanka.

The agency claimed the attack violated customary international law, humanitarian law, and maritime regulations. The report said the assault targeted personnel participating in exercises designed to strengthen maritime security and diplomacy.

It should be noted that on February 28, the U.S. and Israel began military operations against Iran, escalating regional tensions.