The Iranian frigate sunk by a U.S. submarine last week had just left an Indian naval exercise. Now India's political opposition is demanding answers.

A retired U.S. Navy nuclear submarine commander is offering his perspective on Tuesday's torpedo attack that sank an Iranian warship in the Indian Ocean.

Beijing is working to ramp up production of nuclear-powered attack boats and incorporate larger numbers of guided-missile classes into its submarine force, putting the People’s Liberation Army Navy on the path to credibly challenge U.

The men are accused in the sinking of the ARA San Juan, in which 44 crew members died. Victims' families say justice remains incomplete as no high-level political figures have been prosecuted.

Three Australian Navy members were aboard a US submarine that sank an Iranian ship. Prime Minister Anthony Albanese confirmed their presence but stressed they took no part in the attack. The incident occurred off Sri Lanka's coast.

The torpedoing by a U.S. submarine of an Iranian naval vessel in the Indian Ocean "crossed the line" with Tehran saying all bets were now off.

Sri Lanka sent jets to rescue crew of Iranian ship 'Iris Dena' after it sounded a distress call. Sri Lanka denied that the ship was hit by a submarine attack.

Most of China's submarine fleet is diesel-electric, but Beijing is ramping up production of nuclear-powered classes.