The U.S. and Iran have traded strikes for the first time in over a month, marking a major escalation in the conflict and renewing fears of further hostilities.

Iran’s Revolutionary Guard on Monday said it launched an attack on two U.S. bases in Jordan in response to a U.S. strike on Larak Island over the weekend, Iranian media reported.

American forces hit two Iranian rocket launchers on Larak Island on Sunday after the military said the Guard was preparing rockets carrying sea mines for launch into the Strait of Hormuz, U.S. Central Command confirmed to MS NOW.

Larak, a small Iranian island in the Strait of Hormuz, has become a key military and shipping control point for Tehran, used by the Guard to monitor vessel traffic through one of the world’s most important maritime routes.

“Earlier today U.S. forces struck two Iranian launchers on Larak Island. Islamic Revolutionary Guard Corps forces were observed preparing to launch rockets with sea mines into the Strait of Hormuz,” Navy Capt. Tim Hawkins, a U.S. Central Command spokesperson, said in a statement.

“Last week, CENTCOM completed clearing sea mines from the strait’s international shipping routes. U.S. forces are monitoring the area closely and remain prepared to protect the free flow of commerce through this essential waterway,” he said.

Sunday’s attack was the first publicly acknowledged U.S. strike on Iranian positions since late July. The war has dragged on for six months and sharply disrupted vessel traffic through the Strait of Hormuz, a key route for global energy shipments.

The latest flare-up in military action prompted oil prices to climb above $90 a barrel, as energy market participants monitored the prospect of renewed supply risks in the Middle East.

International benchmark Brent crude
 futures with November expiry traded 3.2% higher at $90.90 per barrel on Monday morning, while U.S. West Texas Intermediate crude
 futures with October delivery rose 3.5% to $86.28.