Trump's diesel dilemma — by the numbers

Wholesale diesel prices have more than doubled since the beginning of 2026 through the end of September as both the war in Iran and Russia's war in Ukraine have dramatically cut global supply. Trump has insisted that the war in Ukraine is to blame for high diesel prices. On July 8, Russia banned diesel exports after Ukraine struck its refineries. In the U.S., the price of a gallon of diesel rose nearly 40% between July 6 and Sept. 22.However, the price of diesel had already jumped after the Iran war started and was still 20% above its prewar level when Russia instituted its export ban, making that tightening of supply feel that much more acute.Indeed, both conflicts have created major ripple effects across global energy markets causing major swings, sometimes daily.