India has seized three US-sanctioned tanker ships linked to Iran this month and stepped up surveillance in its maritime zone to curb illicit trade, a source with direct knowledge of the matter said on Monday.
India aims to prevent its waters from being used for ship-to-ship transfers that obscure the origin of oil cargoes, the source added.
The seizures and heightened surveillance follow an improvement in US-India relations. Washington announced earlier this month that it will cut import tariffs on Indian goods to 18% from 50%, after New Delhi agreed to stop Russian oil imports.
Sanctioned vessels Stellar Ruby, Asphalt Star, and Al Jafzia frequently changed their identities to evade law enforcement by coastal states, the source said, adding that their owners were based overseas.
Indian authorities said in a post on X/Twitter on February 6 that they had intercepted three vessels about 100 nautical miles west of Mumbai after detecting suspicious activity involving a tanker in India's exclusive economic zone. The post was later deleted, but the source now confirmed that the vessels had been escorted to Mumbai for further investigation.
The Indian Coast Guard has since deployed about 55 ships and 10 to 12 aircraft for round-the-clock surveillance in its maritime zones, according to the source.
The US Office of Foreign Assets Control sanctioned the vessels Global Peace, Chil 1, and Glory Star 1 last year, whose IMO numbers are identical to those of the ships captured by India.
Two of the three tankers are linked to Iran, with Al Jafzia having carried fuel oil from Iran to Djibouti in 2025 and Stellar Ruby flagged in Iran, according to LSEG data.
The Asphalt Star mostly operated on voyages around China, the data show.
Sanctioned oil and fuel are often sold at deep discounts due to the risks involved, with intermediaries moving cargo through complex ownership structures, false documentation, and mid-sea transfers that complicate enforcement.
US intercepts oil tanker tied to Iran
India's interception of Iran-linked ships comes a day after a similar move by the US.
On Sunday, the US intercepted the Veronica III, an oil tanker tied to Iran that was making its way from the Caribbean Sea to the Indian Ocean, the US Department of Defense said.
Video shared by the DoD showed about 20 soldiers approaching the vessel by helicopter before appearing to board it.
"No other nation has the reach, endurance, or will to do this," the DoD said.