President Donald Trump ordered the Justice Department early Wednesday to investigate major oil companies, accusing them of "gouging" American drivers by failing to pass along the steep drop in crude prices that followed the U.S.-Iran peace deal.

The Truth Social post arrived as the national gasoline average sat near $3.91 a gallon, far below May's wartime peak but still about $1.14 above the level recorded in January, before U.S. forces opened the Iran campaign.

"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.

"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. Gasoline prices better start going down a lot faster than what I'm seeing!"

Trump named no companies.

The math behind the complaint is real, if incomplete.

Pump prices have fallen for six straight weeks, down more than 14% from the May high to roughly $3.906 a gallon, GasBuddy data show.

Over the same window, U.S. crude has slid 23%, and from its March peak, the benchmark is off about 40%.

On Wednesday, Brent crude for August traded at $76.38 per barrel, down 0.91%, while West Texas Intermediate fell 0.94% to $72.52 per barrel.

The selloff has accelerated since Trump and Iranian President Masoud Pezeshkian signed a 14-point memorandum of understanding last week at Versailles, ending the war that began Feb. 28 and reopening the Strait of Hormuz to commercial shipping.

The MOU extends the existing ceasefire 60 days, lifts the U.S. naval blockade, permits Iranian oil exports, and sets the clock on talks over Tehran's nuclear program. Before the war, roughly a fifth of the world's seaborne oil moved through the strait.

Crude prices spiked far harder than they have fallen.

WTI hit $119.47 on March 9, and Brent topped out at $126.41 on April 30, the highest in more than four years, as Iran mined the strait and the U.S. blockaded Iranian ports. Pump prices peaked above $4.50 over Memorial Day weekend, AAA tracking showed.

Energy analysts say crude moves take weeks to reach the pump.

Karen Young, a senior research scholar at Columbia University's Center on Global Energy Policy, called the post "political theater" and told CNBC that state and local taxes, refiner margins, and pipeline lag all sit between a barrel of crude and a gallon of gasoline.

Research cited by Fortune estimates U.S. pass-through at about 13% after a week and roughly 50% over the long run.

The political stakes are immediate.

Republicans face a November midterm with gas still about 41% above pre-war levels, and Trump's directive opens a federal antitrust posture toward an industry he courted on the campaign trail.

The DOJ has yet to describe any investigative steps, charging theory, or timeline.