The US national average diesel price reached $6.505 per gallon on September 21, according to the American Automobile Association, after passing $6 around September 10-11. Prices are roughly 60% higher than a year earlier. The increase is being driven by disruptions linked to the ongoing US-Israeli conflict with Iran, which has affected shipping through the Strait of Hormuz, and by Ukrainian military operations targeting Russian refineries, prompting Moscow to restrict diesel exports. About 20% of global oil flows through the Strait of Hormuz, while Russia has historically supplied much of Europe’s diesel. US diesel inventories have fallen to 106.3 million barrels, about 13% below the five-year average, leaving a narrower supply cushion before the fall harvest season. Brown University estimates that higher diesel prices have added more than $46 billion to US consumer fuel costs since the Iran-related conflict began. Because fuel accounts for 25%-30% of trucking companies’ operating costs, carriers may need to pass higher expenses to shippers and consumers. Farmers without earlier fuel contracts face higher input costs, while diesel demand during harvest could further pressure supplies. Diesel and jet fuel are both middle distillates (refined fuels from similar crude fractions), so stronger diesel demand can also push up jet fuel prices. Refinery utilization and autumn maintenance will be key variables: a significant decline in utilization while inventories remain below average would intensify the pressure.