India, March 5 -- Iran has strongly condemned the United States after a US submarine torpedoed and sank the Iranian naval frigate IRIS Dena in "international waters" in the Indian Ocean, an attack Tehran described as an "atrocity at sea".

The strike killed dozens of Iranian sailors and significantly escalated tensions in the ongoing conflict involving Iran, the United States and Israel.

According to Iranian officials, the vessel was operating in international waters roughly 2,000 miles from Iran's coastline when the attack occurred.

Tehran has warned that Washington will "bitterly regret" setting what it calls a dangerous precedent in maritime warfare.

The incident has intensified fears that the conflict, already spreading across the ...