To appreciate the booming trade in Russian fossil fuels, one need only go to a rooftop cafe along the Bosphorus.

Back in March, while sipping tea on an Istanbul terrace, I watched as, over the course of two hours, at least four tankers — later identified through open-source marine-traffic websites — carried Russian crude and refined products through one of the world’s busiest shipping chokepoints.

A recent report by the Center for Research on Energy and Clean Air (CREA) and the Center for the Study of Democracy (CSD), confirmed what I observed in Istanbul. Turkey has facilitated the flow of Russian oil to the European Union since Russia’s full-scale invasion of Ukraine, enabling the Kremlin to circumvent the bloc’s sanctions and prolonging the war. In 2023, Turkey became the world’s biggest buyer of Russian fossil fuels, importing around €42.2 billion ($45.9 billion) in oil, natural gas and coal from the country — a fivefold increase over the past decade.