Iran uses ghost fleet to break US blockade of Strait of Hormuz

On March 11, the Thai cargo vessel Mayuree Naree was struck by two shells while crossing the Strait of Hormuz, one of the world’s most important waterways between Iran and Oman. A fire erupted in the engine room; 20 crew members were rescued but three were trapped inside. Their bodies were found weeks later when a specialized rescue team boarded the ship, which by then had run aground on Iran’s Qeshm Island coast.

At the same time, a “ghost fleet” of oil tankers continued to navigate the same waters safely. Operating with false flags, disabled signals, and unknown destinations, this secret fleet survives by working outside the traditional rules of maritime commerce.

Iran threatened to block “enemy” ships passing through the Strait of Hormuz — a critical chokepoint for one-fifth of the world’s oil — after the US-Israel war launched on February 28. Navigation through the strait was immediately disrupted due to fears of attack. After a temporary ceasefire on April 8, the US imposed a comprehensive maritime blockade on Iranian ports on April 13. In theory, traffic through the strait should have ceased entirely.

However, tracking data reveals a starkly different reality. An Al Jazeera exclusive investigation monitored 202 voyages by 185 vessels through the strait from March 1 to April 15, both during attacks and crossing blockade lines.

Numbers behind the shadows

To understand how the strait operates under extreme pressure, Al Jazeera’s Digital Investigation Unit monitored the waterway daily, cross-referencing ships’ IMO numbers with international sanctions lists from OFAC (US), the EU, the UK, and the UN. Among the tracked voyages, 77 (38.5%) were directly or indirectly linked to Iran. Notably, 61 ships were explicitly listed on international sanctions lists.

The investigation divided the conflict into three phases to map the fleet’s behavior:

• Phase 1: Open war (March 1 – April 6): 126 ships crossed the strait, peaking at 30 on March 1. Of these, 46 were linked to Iran.
• Phase 2: Ceasefire agreement (April 7–13): 49 ships crossed during the fragile truce. Over 40% of these vessels were linked to Iran, including the Iranian-flagged, US-sanctioned Roshak, which successfully escaped the Persian Gulf.
• Phase 3: US blockade (April 13–15): Despite an explicit blockade, 25 ships crossed the strait.

Breaking the blockade

When the US blockade took effect, the ghost fleet adapted instantly. The Iranian cargo vessel “13448” successfully broke the blockade. Because it is a small vessel operating in coastal waters, it lacks an official IMO number, allowing it to evade traditional sanctions monitoring tools. The ship departed Iran’s Al Hamriya port and arrived in Karachi, Pakistan.

Similarly, the Panama-flagged Manali broke the blockade by crossing the strait on April 14 and again slipped through the cordon on April 17 en route to Mumbai, India.

The investigation also uncovered widespread manipulation of AIS tracking devices. US-sanctioned vessels such as Flora, Genoa, and Skywave deliberately disabled or jammed signals to conceal their identities and destinations.

False flags and shell companies

To disguise true ownership, the ghost fleet relies heavily on a complex network of “false flags” and shell companies. The investigation identified 16 vessels operating under false flags, including registrations from landlocked countries such as Botswana and San Marino, as well as Madagascar, Guinea, Haiti, and Comoros.

The operational network managing these vessels is spread globally. Operator companies are primarily based in Iran (15.7%), China (13%), Greece (over 11%), and the United Arab Emirates (9.7%). Notably, the operators of nearly 19% of observed vessels remain unidentified.

The cost of a parallel system

Despite intense military pressure, energy carriers dominated traffic, with 68 ships (36.2%) transporting crude oil, petroleum products, and gas. Ten of these tankers were directly linked to Iran. Non-oil trade also continued, with 57 bulk and general cargo ships crossing during the open war phase, 41 of which were linked to Tehran.

Before the war, at least 100 ships crossed the Strait of Hormuz daily. Currently, up to 20,000 sailors are stranded on 2,000 vessels across the Persian Gulf — a crisis the International Maritime Organization describes as unprecedented since World War II. Meanwhile, an Iranian ghost fleet navigates seamlessly as part of a parallel maritime system born from 47 years of US sanctions on Tehran. Washington imposed sanctions on Iran after the 1979 Islamic Revolution overthrew the pro-US Shah Mohammad Reza Pahlavi. The two countries have had no diplomatic relations since 1980.