U.S. Navy Executes Historic Submarine Strike Against Iranian Warship

In a military operation not seen since World War II, a U.S. submarine has sunk an Iranian warship in international waters off Sri Lanka’s southern coast using a Mark 48 Advanced Capability torpedo, War Secretary Pete Hegseth confirmed Wednesday.

“An American submarine sank an Iranian warship that thought it was safe in international waters,” Hegseth told reporters during a Pentagon briefing, describing the attack as “a quiet death” and the first successful torpedo strike against an enemy vessel since the 1940s.

The $4.2 million torpedo struck the IRIS Dena, the newest frigate in Iran’s naval fleet, carrying a 650-pound warhead that detonated beneath the vessel’s stern. The weapon is designed not to hit ships directly but to create a massive vapor bubble underneath that breaks the vessel in half.

“This torpedo detonated underneath the stern of the Iranian ship and lifted it up out of the water, and so it sank in a matter of minutes,” explained Thomas Shugart, an adjunct senior fellow at the Center for a New American Security.

Military analysts note this marks only the second time in history that a nuclear-powered submarine has sunk a ship with a torpedo. The previous instance occurred during the 1982 Falklands War when the British submarine HMS Conqueror sank the Argentine cruiser General Belgrano.

The operation demonstrates the overwhelming technological superiority of American naval forces. U.S. nuclear submarines can operate at high speed with virtually unlimited range, constrained only by onboard supplies.

“The U.S. Navy submarines are very highly mobile, very, very quiet, and our crews are extremely well-trained,” Shugart noted. “To hunt down and sink an Iranian ship like that is not a challenging task for a U.S. nuclear-powered submarine.”

The IRIS Dena was not a minor target. It represented significant Iranian naval capability, equipped with surface-to-air missiles, anti-ship missiles, torpedo launchers, and other advanced weaponry. The vessel was the newest frigate in Iran’s fleet, making its loss particularly significant for Tehran’s naval operations.

Sri Lankan authorities reported receiving a distress call at 5:08 a.m. local time Wednesday from the Iranian vessel, which reported an explosion. Sri Lanka’s Foreign Affairs Minister Vijitha Herath confirmed the incident, which occurred outside the country’s territorial waters.

Military experts interpret the strike as a dramatic escalation in U.S. military action against Iran, signaling a fundamental shift in American posture. “It definitely seems to me like a message that the gloves really are off,” said Shugart.

The operation underscores the vast technological gap between U.S. and Iranian naval capabilities. While American submarines are nuclear-powered with advanced weapons systems and unlimited mobility, Iran’s submarine fleet consists largely of aging diesel-electric vessels acquired from Russia decades ago.

“I’m not sure Iran has any operational submarines anymore, but if they were operational, their biggest submarines would be at least 20 or 30 years old,” Shugart explained. “They would be ex-Russian diesel-electric submarines, so they’re not nuclear-powered like the U.S. ones.”

The attack sends an unmistakable message to Tehran about American willingness to employ decisive force. “This strike sent a message that if there are any Iranian warships left or any Iranian government-owned ships, they should expect no mercy,” Shugart added.

The submarine operation likely involved extensive surveillance, forward naval deployments, and precise targeting actions designed to demonstrate U.S. maritime dominance while signaling to Iran that escalation would be met with overwhelming force.

As tensions continue to rise between Washington and Tehran, this historic submarine strike marks a significant turning point in the conflict and demonstrates America’s willingness to employ capabilities not used in combat operations for generations.