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 with a single Mark 48 ADCAP torpedo in the Indian Ocean, marking the first American submarine torpedo kill since World War II. The attack occurred roughly 20 nautical miles south of Sri Lanka as the Dena returned from an international naval review in India. Of approximately 180 crew, 32 were rescued and at least 80 killed. The Mark 48, in service since 1972, detonates beneath a ship's keel to break its hull, and has no reliable defense. The article argues the weapon is critically important for future naval conflicts, particularly in scenarios like a Chinese invasion of Taiwan, where CSIS wargames show undersea dominance is decisive. However, critics note the high cost per round and limited magazine capacity.