A U.S. submarine released dramatic torpedo footage showing the sinking of the Iranian warship IRIS Dena in the Indian Ocean off Sri Lanka, resulting in dozens of sailor casualties. The frigate was returning from naval exercises hosted by India when it was intercepted. This marks the most significant naval engagement of the conflict to date.

Iran has vowed swift retaliation, while the Pentagon described the action as necessary self-defense against threats to U.S. and allied shipping. The incident has sent shockwaves through global maritime insurance markets and prompted emergency consultations among Indian Ocean nations.

Analysts warn the sea war could quickly expand if Iran deploys more naval assets or mines key chokepoints.