The Islamic Revolutionary Guard Corps (IRGC) on Thursday said that it targeted the American tanker shortly after issuing a statement asserting control over shipping movement through the Strait of Hormuz, Reuters reported.

The development signals another escalation in the widening conflict, which has already resulted in more than 1,000 deaths in Iran and the deaths of six American soldiers.

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The reported attack also came less than 24 hours after the US Navy sank the Iranian frigate IRIS Dena in international waters off Sri Lanka's southern coast, pushing the conflict into the Indian Ocean region.

How the Iranian warship was sunk

IRIS Dena had been returning to Iran from India's Visakhapatnam after taking part in two naval exercises last month when it was struck by a US torpedo.

The surprise attack left 87 Iranian sailors dead. Among the survivors were the ship's commander and several senior officers. A total of 32 crew members were rescued, while more than 60 sailors remain missing.

A video released by the US Pentagon showed a large explosion after the torpedo struck the vessel, tearing apart its rear section before it sank.

The US is believed to have used the Mark-48 heavyweight torpedo, a key weapon in the American Navy's submarine warfare system. It is also the first time since World War II that an American submarine has sunk a ship using a torpedo.

Iran warns of consequences

US Defence Secretary Pete Hegseth described the operation while speaking to reporters.

"An American submarine sank an Iranian warship that thought it was safe in international waters," Hegseth said, adding that the vessel died a "quiet death".

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Iran's Foreign Minister Abbas Araghchi strongly condemned the attack and vowed retaliation.

"Frigate Dena, a guest of India's Navy, was struck in international waters without warning. Mark my words: The US will come to bitterly regret the precedent it has set," Araghchi tweeted.

In recent days, the United States has increased strikes on Iranian naval assets, including attacks on naval bases along the Persian Gulf and a container ship that had reportedly been converted into a drone carrier.