US Submarine Torpedoes Iranian Frigate IRIS Dena off Sri Lanka—First Confirmed American Sub Kill Since 1945

The last time U.S. forces sank Iranian warships was Operation Praying Mantis (18 April 1988), but that action used surface ships and aircraft in the Gulf; a submarine torpedo kill recalls WWII’s Battle of the Atlantic more than modern limited wars. Strategically, the strike drags the broader U.S.–Israel–Iran conflict 2,000 mi east into the Indian Ocean, a waterway that had been trending toward multipolar stewardship since the 2004 tsunami spurred regional naval cooperation. It also tests the UNCLOS regime: Washington acted in another state’s EEZ without consent, while Tehran invokes Article 51 self-defense and Sri Lanka scrambles to assert limited jurisdiction. Over a 100-year horizon, this incident may signal a return to great-power submarine coercion on the global commons, eroding the post-1970s norm that major naval combat stays near littorals and chokepoints. If unchecked, it could normalize high-seas torpedo diplomacy much as the 1964 Gulf of Tonkin skirmish catalyzed deeper U.S. engagement in Vietnam.