The shadow fleet is a network of oil tankers that transport sanctioned crude oil primarily from Iran, Russia, and Venezuela to buyers including China, India, and Turkey. These vessels are typically uninsured by Western underwriters, fly flags of convenience, and use ship-to-ship transfers to obscure cargo origins. The U.S. Treasury's OFAC tracks and sanctions shadow fleet entities. The 2026 Iran war disrupted the Iran-to-China shadow fleet pipeline, with ripple effects on Russia's ability to fund the Ukraine war through the same discount oil networks.