President Donald Trump said the U.S. would strike back at Iran after a recent attack that targeted a military base in Jordan, as the war in the Middle East flared up again following a pause in hostilities.

“We’ll be hitting them hard,” Trump said in a phone interview, Fox News reported Wednesday, adding that “they’re going to get a beating.”

The comments sent oil surging. Brent settled near $91 a barrel, spiking about 8%. A days-long halt to strikes ended Tuesday night after U.S. forces said they were targeted by Iran — in what Trump called a “surprise attack” — while Iran’s state-run IRIB News said the U.S. struck a location in the country’s West Azerbaijan province.