The OSINT Report | Special Intelligence Brief | March 4, 2026On March 4, 2026, the rules of naval warfare changed. For the first time since 1945, a United States nuclear-powered fast-attack submarine has conducted a lethal combat sinking of an enemy warship. The target: the Iranian Moudge-class frigate, IRIS Dena.In this special report, we break down the verified OSINT data and strategic shifts surrounding Operation Epic Fury in the Indian Ocean. From the “Keel-Snap” physics of the Mark 48 ADCAP torpedo to the total collapse of international naval norms, this is a fundamental rewrite of the rules of engagement.In This Brief:The Opening: Why the sinking of the Dena marks the end of 80 years of U.S. naval tradition.The Confirmed: Verified data on the strike location south of Sri Lanka and the 80%+ casualty rate.The Observed: Analyzing the “Quiet Death” strike—how a single torpedo snaps a 1,500-ton warship in two.The Assessed: The move toward Horizontal Escalation and why the “Diplomatic Safe-Harbor” of naval exercises is officially dead.The Tactical Shift: How subsurface dominance has rendered surface-level deterrents obsolete.The Unknown: The electronic environment, “signature-less” warfare, and the strategic silence from New Delhi.What to Watch For: Why an Iranian attempt to close the Strait of Hormuz will likely trigger the systematic dismantling of their remaining fleet.