War on Iran: What is Tehran's 'shadow fleet' really and how does it work?

What Happened

Following the collapse of a planned US–Israeli peace deal, the United States reimposed a naval blockade on Iranian ports, intensifying the economic pressure on Tehran. To circumvent decades of US sanctions, Iran operates a 'shadow fleet'—a network of roughly 400 ageing tankers that obscure their ownership, turn off mandatory tracking signals, and conduct ship-to-ship transfers to disguise the origin of Iranian crude. These vessels sail under flags of convenience from states such as Liberia, Panama, and Malta, with ultimate ownership often traced to IRGC-affiliated billionaires or Chinese businessmen. China is the largest buyer, importing an estimated 1.4 million barrels per day of Iranian oil in 2025, routed through small private 'teapot' refineries in Shandong and recorded as originating from Malaysia or Indonesia to avoid US secondary sanctions. The fleet also supplies jet fuel to Myanmar, drawing criticism from human rights groups.

Key Actors

Why It Matters

The shadow fleet is a critical lifeline for the Iranian economy, enabling the regime to fund its 'Axis of Resistance' network and withstand Western pressure. It exposes the limits of unilateral US sanctions when a major power like China disregards them, and it raises serious legal, environmental, and safety concerns under the International Maritime Organization's framework, as the aging, unregulated ships pose spillage and labor risks.

Watch For

Monitor US enforcement actions such as vessel seizures or sanctions designations against shipping entities; IAEA reports and any revived nuclear deal talks that could alter sanctions scope; China's customs data for discrepancies that reveal continued Iranian oil imports; UN IMO pressure on flag states to crack down on safety violations; and potential escalation through direct naval interdiction in the Persian Gulf or Strait of Hormuz.