US says submarine strike demonstrates naval strength and ability to operate undetected in global waters
The United States (US) has confirmed that one of its Navy submarines sank an Iranian warship in the Indian Ocean using a torpedo. The incident marks a serious escalation in tensions between the US and Iran.
On March 4, 2026, US Defense Secretary Pete Hegseth confirmed that an American submarine fired a Mark 48 torpedo at the Iranian frigate IRIS Dena, destroying it. He said the ship was operating in international waters and likely believed it was safe before the strike hit.
Hegseth described the attack as a “quiet death.” He and Chairman of the Joint Chiefs of Staff General Dan Caine said this was the first time since World War II that a US submarine had sunk an enemy warship with a torpedo. They called it a historic moment in modern naval warfare.
Attack Happened Near Sri Lanka
US officials said the strike took place in the Indian Ocean, about 40 to 50 nautical miles south of Galle, Sri Lanka. The Pentagon did not reveal the name or class of the US submarine involved for security reasons.
The IRIS Dena was part of the Islamic Republic of Iran Navy’s Southern Fleet. It was a Moudge-class frigate.
Sri Lankan authorities said they received a distress call from the Iranian ship early in the morning. Even though the incident happened outside Sri Lanka’s territorial waters, it was within the country’s search-and-rescue zone. Sri Lanka quickly sent naval ships and aircraft to help survivors.
Many Killed, Dozens Rescued
The attack caused heavy losses. Sri Lankan officials rescued 32 crew members from the sea and took them to a hospital in Galle. They were seriously injured.
Reports say the IRIS Dena had around 180 people on board when it was struck. Early estimates suggest that between 80 and more than 150 sailors may have died. However, Iran has not yet released official casualty numbers. Rescue teams are still searching for missing crew members.
US Department of War Share Strike Video
The US Department of Warreleased video footage showing the torpedo hitting the Iranian warship on X (formerly Twitter), making the visuals public.
The video reportedly shows the moment the torpedo strikes the ship’s hull, followed by a powerful explosion and the vessel sinking into the sea.
US officials presented the footage during a press briefing to show the accuracy and strength of the operation. They described the strike as decisive and strategically important.
Also Read: Strait of Hormuz Closed: Is This the Moment the US–Israel–Iran War Turned Global?
Part of Larger US Military Campaign
The submarine attack is part of a wider US military campaign against Iranian military targets. In recent weeks, tensions between the US, Israel, and Iran have increased sharply.
General Dan Caine said US forces have hit more than 2,000 targets and destroyed over 20 Iranian naval vessels in the broader operation. US and Israeli leaders have said their goal is to weaken Iran’s military power, including its navy, missile systems, and command centers.
President Donald Trump has previously said the US wants to stop Iran from expanding its military influence and possible nuclear ambitions.
Iran Vows Retaliation
The sinking of the IRIS Dena has increased tensions in the region. Iranian officials have warned that they will retaliate against US, Israeli, and allied interests in the Middle East.
In recent days, reports have mentioned missile launches and strikes in different parts of West Asia. Many countries in the region remain on alert as the conflict continues.
Legal and Political Debate
Because the attack happened in international waters, experts have started discussing whether the strike follows international maritime law. Some analysts are questioning whether the action qualifies as self-defense under global legal standards.
In the United States, lawmakers are also debating military authority and war powers as the conflict grows. The strike has added to political discussions about how far the US should go in its actions against Iran.
Global Impact on Shipping and Oil
The rising conflict has already affected important shipping routes, especially near the Strait of Hormuz, which is a key path for global oil transport. Oil prices have increased as markets react to the tension.
Shipping companies and governments are watching the situation closely, worried that further military actions could threaten commercial ships and global trade.
A Rare Event in Modern Naval History
Military experts say this is a rare event in modern times. The United States has not sunk an enemy warship with a submarine-fired torpedo since World War II. That makes this strike historically significant.
Submarines are usually used for secret missions and deterrence. By using a torpedo to destroy a surface warship, the US showed its naval strength and willingness to take strong military action.
Situation Still Uncertain
Rescue operations are still ongoing, and Iran has not yet shared detailed information about casualties or its next steps. The situation remains tense and could develop further in the coming days.
The sinking of the IRIS Dena has marked a major turning point in the US-Iran conflict and has raised fears of a wider regional confrontation.
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