Iran Submarine Sinks Warship: US & Iran Clash Over Arms

The United States and Iran have offered conflicting accounts regarding the sinking of an Iranian warship in the Indian Ocean last week, with Washington disputing Tehran’s claim that the vessel was unarmed. Iranian officials maintain the ship was operating in a noncombat role.

Dispute Over Armament

The U.S. Indo-Pacific Command on Sunday rejected Iran’s assertion that the warship IRIS Dena was unarmed when it sank in international waters off Sri Lanka on March 4. INDOPACOM called Iran’s claim “false” in a statement on X.

Tehran has repeatedly characterized the warship as defenseless, stating it was returning home after participating in a naval exercise. An Indian navy official, speaking on condition of anonymity, said the Iranian vessel was not “entirely unarmed” and had taken part in drills alongside other countries’ warships.

Some experts suggest that ships participating in such events typically do not carry a full combat load of live munitions unless scheduled for live-fire drills, generally carrying only tightly-controlled ammunition limited to specific exercises.

Rahul Bedi, an independent defense analyst based in India, said the vessel may have used some limited non-offensive ammunition during the naval exercises, but protocol requires “the participating platforms to be unarmed.” He added that the precondition for participating in fleet reviews is that vessels arrive unarmed, a standard practice of the Indian Navy and many others.

Conflicting Statements

Iran’s Deputy Foreign Minister Saeed Khatibzadeh said Friday that the warship, sunk by a U.S. torpedo, had not been carrying weapons and accused Washington of targeting a ceremonial vessel. He stated the ship was “by invitation of our Indian friends, attending an international exercise. It was ceremonial. It was unloaded. It was unarmed.”

The IRIS Dena sank on March 4 in the Indian Ocean near Sri Lanka after being struck by a torpedo from a U.S. submarine, according to American and Iranian officials. The Sri Lankan navy rescued 32 sailors and recovered 87 bodies.

U.S. Defense Secretary Pete Hegseth described the IRIS Dena as a “prize ship” that “died a quiet death.” Iran’s Foreign Minister Abbas Araghchi described the attack as “an atrocity at sea,” emphasizing that it had been “a guest of India’s Navy.”

Disputes over whether the vessel was armed have intensified tensions surrounding the incident, which occurred as it was returning from multinational naval exercises in India, and raised questions about its operational status when attacked. India’s defense ministry stated after the exercises that “live firings as part of surface gun shoots, as well as anti-air firings, were also undertaken” by participating vessels.

The sinking highlighted how the U.S.-Israeli war with Iran is spreading beyond the Middle East. Two other Iranian vessels — the IRIS Bushehr and IRIS Lavan — are docked in Sri Lanka and India after seeking assistance from the two countries.