Donald Trump has said that the interim agreement to end the US-Iran war is over, as the battle to control the Strait of Hormuz escalates sharply.

Asked at a Nato summit in Turkey whether the memorandum of understanding (MoU), which provides a framework for US-Iran peace talks, was over, Trump said: “To me, I think it’s over. I don’t want to deal with them. They’re scum. They’re sick people. They’re led by sick people. As far as I’m concerned, it’s just a waste of time dealing with them.”

Military action between the US and Iran is more intense than at any time since a ceasefire on 8 April brought an end to the five-and-a-half-week-long war. At the heart of the renewed conflict is Iran’s determination to retain its control of the Strait of Hormuz, which was its most important gain in the war and its main source of diplomatic leverage, while the US wants to erode this advantage.

In practical terms, this means Iran insists that commercial vessels, above all the oil and liquefied natural gas (LNG) carriers, gain Iranian permission for their voyages and take a shipping route through the north of the Strait close to Iran. The US has encouraged vessels to take a southern route, without receiving Iranian permission, hugging the Omani coastline.