Hormuz Monitor: Iran Says 35 Ships Crossed Strait as Oil Tankers Pile Up Off Kharg Island

The crisis surrounding the Strait of Hormuz intensified over the past 24 hours as Iran insisted on enforcing a permit-based transit system for vessels crossing the strategic waterway, while Gulf states and the United States rejected any attempt by Tehran to impose unilateral controls or transit fees.

At the same time, shipping intelligence data showed Iranian oil tankers increasingly congested off Kharg Island under mounting sanctions pressure, even as the first Saudi crude tanker since the outbreak of the war successfully approached Japan after transiting the strait.

The developments are part of growing disruptions affecting global energy flows and maritime supply chains through one of the world’s most critical oil transit routes.

Iranian state media, citing the naval forces of the Islamic Revolutionary Guard Corps, reported that 35 vessels crossed the Strait of Hormuz during the past 24 hours after receiving prior authorization from Tehran.

According to Iranian officials, the vessels included oil tankers, container ships, and commercial cargo vessels, all escorted under IRGC naval protection and coordinated through Iranian maritime authorities.

The move comes as Iran pushes for a new transit framework in Hormuz that would require ships to obtain permits, share vessel information, coordinate with Iranian authorities, and potentially pay safe-passage fees.

Shipping analytics firm Kpler said vessel traffic through the strait remained limited despite modest improvements.

According to Kpler’s tracking data, confirmed crossings rose to 10 vessels on May 20, compared with four vessels the previous day and 22 vessels on May 16.

Iranian authorities, however, claimed that 26 ships were moving through the waterway after completing approval procedures with Tehran.

Kpler noted that most vessel activity was concentrated along a west-to-east commercial corridor, while no new Iranian export loadings were observed.

The company added that Tehran appears to be formalizing a more structured permit-based transit regime supervised by IRGC naval forces, turning access to the strait into an increasingly politicized process vulnerable to sudden disruptions.

Meanwhile, Saudi Arabia, Qatar, Kuwait, United Arab Emirates, and Bahrain formally rejected Iran’s proposed “Gulf Strait Authority,” which Tehran intends to use to oversee vessel transit through Hormuz.

In a message circulated through the International Maritime Organization, the Gulf states warned commercial ships and cargo operators against dealing with the Iranian authority or using maritime routes designated solely by Tehran.

The Gulf countries argued that Iran’s proposed corridor would effectively push vessels into Iranian territorial waters, potentially enabling Tehran to impose transit fees and exert broader control over maritime navigation.

The issue carries major implications for global shipping companies, given that the five Gulf states are among the world’s leading energy exporters.

The IMO had previously stated that imposing transit charges in the Strait of Hormuz would be unacceptable under international maritime norms, a position also backed by several major global commodity traders.

US Secretary of State Marco Rubio said Friday that any Iranian attempt to impose fees on vessels crossing Hormuz would be “unacceptable.”

Speaking ahead of a NATO meeting in Helsingborg, Sweden, Rubio stressed that freedom of navigation through international waterways must be preserved and warned against unilateral restrictions on global trade routes.

Shipping intelligence company Windward reported a sharp rise in Iranian-linked oil tankers anchored off Kharg Island, Iran’s primary oil export terminal.

According to Windward, the number of tankers stationed near the island surged 93% over the past week.

AIS tracking data showed 27 tankers anchored near Kharg Island as of May 21, including 18 very large crude carriers (VLCCs), up from 14 vessels a week earlier.

All of the ships were operating “dark,” meaning they had disabled automatic identification system transmissions to conceal their movements.

Meanwhile, the number of tankers waiting near Chabahar declined to 12 dark vessels, including five VLCCs, after peaking at 16 ships on May 16.

Analysts believe Chabahar, located on the Gulf of Oman near the Pakistani border, is increasingly being used as an alternative holding area for vessels rerouted due to the tightening US blockade on Iranian ports since April 13.

According to estimates from Vortexa, around 108 tankers are currently carrying roughly 143 million barrels of Iranian oil at sea, including approximately 32 million barrels being used as floating storage.

Windward estimates that nearly two-thirds of the tankers associated with Iranian oil exports are currently stranded in the Gulf of Oman or the Arabian Gulf, while the remainder are waiting near China or close to Malaysia’s Riau archipelago.

In a significant development for Asian energy markets, the supertanker Idemitsu Maru successfully transited the Strait of Hormuz carrying approximately two million barrels of Saudi crude oil bound for the Aichi refinery in Japan.

The shipment marks one of the first confirmed Saudi crude deliveries to East Asia through Hormuz since the outbreak of the regional conflict, underscoring cautious efforts to restore limited oil flows despite ongoing security risks.