Global oil prices spiked Sunday night after U.S. President Donald Trump said the United States would move to blockade the Strait of Hormuz following the collapse of peace talks with Iran.

U.S. crude jumped roughly 8%, climbing above $104 per barrel, while international benchmark Brent crude rose more than 7% to around $103 per barrel. Wholesale gasoline prices increased by 6%, and heating oil—often used as a proxy for jet fuel—surged 10% in early trading.

Financial markets reacted sharply. Futures tied to the S&P 500 fell 1%, Nasdaq 100 futures dropped 1.3%, and Dow futures declined by more than 500 points.

In a post on Truth Social, Trump said the U.S. Navy would begin enforcing the blockade immediately.

“The United States Navy will begin the process of blockading any and all ships trying to enter or leave the Strait of Hormuz,” he wrote. He added that naval forces had also been directed to intercept vessels in international waters that had paid transit fees to Iran.

The Strait of Hormuz is a critical global energy corridor, handling a significant share of the world’s oil and liquefied natural gas shipments. Prior to the conflict, hundreds of vessels passed through the waterway daily. Since hostilities began on February 28, however, traffic has dropped sharply, with fewer than 10 ships transiting the strait on most days.