Shadow Fleet Evades Blockade: How Iran Bypassed US Naval Restrictions in the Strait of Hormuz

A new investigation has revealed how a covert “shadow fleet” of vessels managed to navigate the strategically vital Strait of Hormuz despite heightened conflict and a US-imposed naval blockade. The findings highlight significant gaps in maritime enforcement during a period of escalating tensions in the region.

The situation drew global attention on March 11, when the Thai cargo ship Mayuree Naree was struck by two projectiles while transiting the strait. The attack caused a fire in the engine room, leading to the rescue of 20 crew members, while three sailors tragically lost their lives. The vessel later ran aground near Qeshm Island.

At the same time, dozens of tankers continued to pass through the same high-risk waters undeterred. These ships, operating under what experts describe as a “shadow fleet,” reportedly used deceptive tactics such as fake national flags, shell companies, and disabled tracking systems (AIS) to conceal their identity and routes.

Tensions in the region escalated after Iran warned it could block “enemy” vessels following the outbreak of conflict involving United States and Israel on February 28. Although a temporary ceasefire was declared on April 8, the US moved to impose a full naval blockade on Iranian ports by April 13, aiming to halt maritime traffic.

However, an open-source investigation by Al Jazeera revealed that maritime activity never fully stopped. Analysts tracked 202 voyages made by 185 vessels between March 1 and April 15, indicating that traffic continued despite the risks and restrictions.

The investigation relied on cross-referencing International Maritime Organization (IMO) numbers—unique identifiers assigned to commercial ships—with global sanctions lists from agencies including the US Treasury’s Office of Foreign Assets Control (OFAC), the European Union, the United Kingdom, and the United Nations.

Experts say the use of shadow fleets exposes vulnerabilities in global maritime monitoring systems, allowing sanctioned or high-risk vessels to continue operating beyond the reach of traditional enforcement mechanisms. The development raises concerns about the effectiveness of naval blockades and the broader implications for global oil supply and maritime security.