President Donald Trump has instructed the Justice Department to investigate oil companies he accuses of failing to pass on falling crude costs to American consumers at the gas pump.

Trump made the announcement in a late-night post on Truth Social, published shortly after midnight, without naming any specific companies in his message.

“The big Oil Companies are not dropping their price at the pump commensurate with the sharply lower prices they are paying for Oil,” Trump wrote in the post.

“Those prices are dropping like a rock! In other words, customers are being ‘gouged.’ I have instructed the DOJ to immediately start looking into this,” he continued.

Trump added a direct warning to the industry: “Gasoline prices better start going down a lot faster than what I’m seeing!”

The Justice Department did not respond to an overnight request for comment following the president’s announcement.

Brent crude, the global benchmark for oil, was trading at roughly $75 per barrel at the time, down sharply from peaks exceeding $100 following U.S. and Israeli strikes against Iran on February 28.

The crude price had also fallen from approximately $86 a barrel recorded just one month prior, representing a significant decline over a relatively short period.

At the pump, the U.S. national average for gasoline stood at $3.926 per gallon, down from $4.529 recorded a month earlier, according to data from AAA.

Gasoline prices had fallen for a sixth consecutive week, driven in part by ongoing U.S.-Iran peace talks and the planned reopening of the Strait of Hormuz, through which approximately 20 percent of the world’s oil supply travels.

Despite the sustained decline at the pump, Trump argued that the reduction was neither sufficient nor proportionate to the drop in underlying crude oil costs.

The investigation order reflects the administration’s growing pressure on the energy sector to translate commodity price relief into direct consumer savings, with Trump framing the gap between crude and retail prices as deliberate consumer exploitation.