The U.S. national average for diesel reached a record $6.27 a gallon on Tuesday, according to the American Automobile Association (AAA), about $2.58 above its level 12 months earlier. Prices first exceeded $6 last Friday, when the average was $6.06. Disruptions linked to the war between the U.S. and Iran, Ukrainian drone attacks on Russian refineries and a strike on a major Saudi pipeline have tightened global fuel supplies. California recorded the highest state average at $8.21 a gallon. Because diesel powers trucking, agriculture and maritime shipping, the increase is feeding costs throughout the supply chain. The Trump administration has considered temporarily banning refined-product exports, but ING analysts said that would provide only short-term relief and could eventually reduce refinery output. Prices have risen from $3.76 a gallon when the conflict began in late February, surpassing the previous record of $5.81 set in June 2022. ING estimates the shipping and Russian export disruptions have removed about 20% of diesel normally transported by sea. The increase is also complicating President Donald Trump’s affordability agenda and has raised expectations that the Federal Reserve will increase interest rates on Wednesday.