WASHINGTON (AP) — The U.S. military said it shot down four Iranian drones that were launched toward the Strait of Hormuz on Friday and then struck some of the Islamic Republic’s coastal surveillance radar sites in response.

“The attack drones posed an immediate threat to regional maritime traffic,” U.S. Central Command said on social media. The military is enforcing a blockade on Iranian ports in response to Tehran’s chokehold on the crucial corridor for global oil and natural gas shipments, which has sent energy prices spiking.

It was the latest in back-and-forth attacks that have strained the tenuous ceasefire in the war and efforts to reach a deal to extend that truce.

Earlier this week, Iranian drones heavily damaged a passenger terminal at Kuwait’s main airport, killing one person, wounding dozens and briefly closing the airfield.