Mark 48 Torpedo Scores First U.S. Submarine Kill Since WWII, Sinking Iranian Frigate

In March 2026, a U.S. Navy fast-attack submarine sank the Iranian Moudge-class frigate IRIS Dena in the Indian Ocean using a single Mark 48 ADCAP torpedo, marking the first American submarine torpedo kill since World War II. The weapon, in service since 1972, detonates beneath a ship's keel to break its hull, and has no reliable defense. The sinking occurred approximately 20 nautical miles south of Sri Lanka as the Dena returned from an international naval review in India; at least 80 of roughly 180 crew were killed. The article argues the Mark 48 remains critically important for undersea warfare, citing CSIS Taiwan wargames where submarine dominance proved decisive, but notes limitations including high cost per round and limited magazine capacity that could be exhausted within a week of intense conflict.