President Donald Trump said on September 28 that the United States is “very seriously” considering restrictions on diesel exports to ease a domestic supply crunch and bring down prices.

The White House is also weighing tax relief on red-dyed diesel, the lower-tax fuel normally reserved for off-road and farm use, as another lever to reduce costs for truckers and farmers. Reuters reported that officials are studying how far they can stretch the rules.

American drivers and hauliers have faced sharply higher fuel prices since the US-Israeli war with Iran disrupted shipments through the Strait of Hormuz earlier this year. Diesel is the lifeblood of freight, so sustained high prices feed through to the cost of goods.

Any export limits would mark a sharp break with America’s role as a major refined-fuel supplier to Europe and Latin America, and analysts warned the move could rattle global diesel markets even as it offers relief at home.