Fuel costs for U.S. airlines jumped 85% in May to nearly $6.7 billion as the Middle East conflict drove ‌up prices, the U.S. Transportation Department said on Monday.

Airlines spent $3.62 billion on fuel in May 2025, compared with $6.66 billion in the same month this year. The cost per gallon of fuel in May ​was $4.09, up $1.88 over May 2025, USDOT added. Jet fuel costs in recent weeks have sharply dropped as tensions eased between Iran and the United States.

Fuel costs in April jumped by about 80% to nearly $6.5 billion.

Jet fuel prices are down around 40% from their highs in April, but oil prices rose more than 2% on Tuesday after reports of attacks on vessels near the Strait ‌of Hormuz revived fears of disruptions to shipping through the critical energy transit route.

Airfares rose significantly after the Iran war began and have not yet fallen as a result of declining jet fuel prices.

As jet fuel prices surged, ​U.S. airlines raised ticket prices and bag fees, and cut schedules, but those steps only offset part of the rise in fuel costs.

Delta Air Lines, United Airlines, American Airlines and Southwest Airlines account for about 80% of U.S. domestic flights.

(Reporting by David Shepardson;Editing by Nick Zieminski and Bill Berkrot)