On Friday, June 5, 2026, maritime analytics firm Kepler reported that four Iranian-flagged oil tankers passed through the Strait of Hormuz on Monday, June 1, marking the first such transit since the United States imposed a blockade on Iranian ports.
According to data released by the company on Thursday, the tankers Hilda, Amber, Sylvia 1, and Happiness 1 were tracked passing through the strategic waterway. Together, the vessels were carrying approximately seven million barrels of crude oil.
All four tankers had loaded their cargoes in April 2026 at Kharg Island, Iran’s main oil export terminal, which under normal circumstances handles roughly 90 percent of the country's crude oil exports.
Kepler, which monitors maritime traffic using satellite imagery, reported that the vessels transited the Strait of Hormuz with their Automatic Identification System (AIS) transponders switched off.
According to Agence France-Presse (AFP), these tankers typically transfer Iranian crude to offshore areas near Malaysia and Singapore, where ship-to-ship transfers take place before the oil is delivered to final customers, often in China. Iranian authorities have long been accused of using such methods to circumvent international sanctions.
The report added that the four vessels initially continued operating despite the conflict involving Iran, Israel, and the United States, but suspended their activities on April 13, 2026, when the U.S. military, acting under orders from President Donald Trump and in response to Iran’s closure of the Strait of Hormuz, imposed a blockade on Iranian ports.
Kepler's data further indicates that three other tankers linked to Iran had previously defied the blockade on April 15, 2026. Since then, no other Iranian-linked vessels had reportedly attempted a similar passage until this week's transit.
