US forces struck Iranian coastal radar sites on Saturday after shooting down drones launched by Iran towards the Strait of Hormuz, the US military said, in the latest escalation complicating efforts to end the war between the two countries.

The US military believed the four Iranian drones were targeting regional maritime traffic, an official said.

US Central Command said on social media that the US then struck Iran’s surveillance ‌sites in Goruk and Qeshm Island, which are both on the Strait of Hormuz.

“The attack drones posed an immediate threat to regional maritime traffic,” it said. It hit the radar sites, including an island in the strait, “to defend against further attacks”.

The US and Iran have been engaged in largely indirect negotiations to secure an interim deal to halt the three-month-old war that would leave issues including Iran’s nuclear programme to further negotiations.

As part of any agreement, Tehran wants access to billions of dollars in oil revenue, waivers on sanctions on crude exports, the lifting of a US blockade on its ports and leverage over the strait. Iran has effectively blocked the strait, where about a fifth of the world’s oil transited before the war.

Despite the attacks raising new concerns that the ceasefire could collapse, President Donald Trump told reporters on Friday that “the situation with Iran seems to be going quite well”.

“We’re going to come out of Iran very quickly and it’s going to be very strong one way or the other, whether it’s a piece of paper or the very tough way,” Trump said at an event with farmers in Wisconsin.

“The very tough way is maybe the easier way, but we’re going to come out, and your fertiliser prices are going to go way down, just like they were four months ago.”

Trump is facing mounting domestic political pressure due to ⁠rising gas prices to bring the unpopular war to an end. He told NBC that while most of Iran’s drone and missile manufacturing facilities had been destroyed, the Iranians still ‌have access to about a fifth of their missiles.

“They have some missiles, they have some drones. I would say percentage wise, maybe 21-22 per cent of their missiles. It’s a lot of missiles, but it’s not what it was when we first attacked,” Trump told NBC News’ “Meet ‌the Press” programme, according to excerpts released by the network on Friday.

When asked why Iran’s leaders – if as desperate as he had portrayed them – were ⁠not more inclined to strike a deal, ⁠Trump said: “Because they are strong. They’re proud. There are things they never thought they’d be doing that they’re going to have to do, they’ve got no choice, and it takes a little while.”

Israel and the US ‌launched the war with strikes on Iran in late February.

Additional reporting by Associated Press