The sinking of an Iranian warship by a U.S. submarine off Sri Lanka has exposed limits in Indian Prime Minister Narendra Modi’s claim that New Delhi acts as a regional “guardian” of maritime security, according to analysts and political critics.

The Iranian frigate IRIS Dena was struck by a U.S. torpedo in international waters in the Indian Ocean earlier this week, killing dozens of sailors and widening the geographical scope of the U.S.-Iran conflict.

Indian authorities took more than a day to formally respond to the incident despite it occurring close to waters where India frequently promotes itself as a key security provider, raising questions about New Delhi’s ability or willingness to influence events in its immediate maritime neighbourhood.

The episode has sparked debate in India about the government’s regional security narrative, particularly Modi’s long-standing emphasis on India as a “net security provider” in the Indian Ocean.

Critics argue that New Delhi’s muted reaction underscores the limits of that posture when major powers such as the United States intervene militarily.

U.S. Defence Secretary Pete Hegseth confirmed that an American submarine sank the vessel with a torpedo, saying the Iranian warship had believed it was safe in international waters.

Sri Lankan authorities said the ship sent a distress signal before sinking, and rescue teams recovered dozens of bodies while saving more than 30 sailors.

The vessel had been returning from a naval exercise in India, according to officials, adding to the diplomatic sensitivity for New Delhi as the wider U.S.-Israel campaign against Iran intensifies.

The attack marks a rare instance of a submarine sinking a surface warship and signals Washington’s willingness to expand military operations against Iranian forces beyond the Middle East into the Indian Ocean.

India has not condemned the strike outright and has instead called for restraint, reflecting its delicate balancing act between maintaining ties with Western partners and preserving longstanding relations with Iran.

Analysts say the incident highlights the challenges facing India’s ambitions to shape security dynamics in the region as great-power competition intensifies.