Donald Trump EPA via BBC Donald Trump's latest statements about Iran and the chances of a deal should be taken seriously, as he is, after all, the president of the United States. Trump told the military alliance summit in Turkey: "I don't want to deal with them anymore, they're scum. You know what scum is? They're scum. They're sick people. They're led by sick people. And they're cruel, violent people." "And if they had a nuclear weapon, they would use it. As far as I'm concerned, [the ceasefire] is over." But would these be his last words on the subject? Certainly not. Trump has continually spoken about the war and the memorandum of understanding (MOU) that is being negotiated. His words have oscillated between declarations of victory, threats of annihilation of Iranian civilization and support for negotiations. He later reiterated his latest threats, saying the US "will probably hit them harder again tonight." The US ability to strike Iran, causing great damage, is not in doubt. But what they failed to do was break the regime's will to abandon any of its fundamental demands, starting with control of navigation through the Strait of Hormuz. Amid his most recent verbal attack, implicit was his acceptance that negotiations would continue. They were suspended while Iran held the wake of its former supreme leader, Ayatollah Ali Khamenei, murdered by Israel and the US on the first day of the war, on February 28. Trump was asked whether the exchange of attacks between the US and Iran – and, by extension, some of the United States' Arab allies in the Gulf – meant an end to negotiations between them. Referring to his top negotiators, Steve Witkoff and Jared Kushner, he said: "I don't care, they can negotiate. But I think they're wasting their time." Of the Iranian regime, Trump said: "They're a bunch of liars." This could be interpreted as yet another admission that the US president, despite his bravado, has no better alternative than negotiating with Iran. With Israel, the US has tried, unsuccessfully, to destroy the Iranian regime. Trump says ceasefire with Iran is over But the negotiation process is fragile. A source among the mediators trying to make the negotiations work said the latest development is "a setback, without a doubt." The atmosphere is considered "very tense". This is a diplomatic way of saying that the events of the last few days present a dire scenario for negotiations between two powers that have no confidence that the other will keep its word if a deal is reached. At the heart of the recent exchanges of military actions between Iran and the US is the Tehran regime's determination to maintain control of the Strait of Hormuz. Its ability to block the passage of ships carrying essential items, including a fifth of the world's oil and gas supplies, gives it strong leverage over the global economy. It is a much more effective pressure tool than the simple possibility of developing a nuclear weapon. Iran will not agree to give up control of the Strait of Hormuz. That is why he is willing to risk the memorandum of understanding – full of potential concessions advantageous to Iran – to make it clear that there is no going back. It is willing to bet on a continuous war to protect what it considers its strategic rights in the Strait. The regime in Tehran felt emboldened by the failure of the US and Israel to destroy it. The supreme leader's funeral demonstrated that the Islamic regime has a solid core of support. The funeral of Iran's late supreme leader Ali Khamenei was held this week NurPhoto via Getty Images via BBC Internal opposition has not disappeared. But the regime's relentless use of force to suppress protests, killing thousands of people in January for demonstrating in the streets, has forced it to keep a low profile. If the escalation between the two sides can be stopped, mediators involved in the negotiation process believe it is possible to reach an agreement with Iran that allows ships to pass through the Strait. Such a deal would have to be part of a broader pact that unlocks Iranian assets held abroad, allows Iran to sell its oil and, crucially for the regime, recognizes Iranian authority over the Strait. In return, Iran would have to accept limits on uranium enrichment, allow UN nuclear inspectors to return and account for stockpiles of what Trump calls "nuclear dust" — in other words, uranium already enriched to levels close to those that could be used to make a nuclear weapon. But the events of the last 24 hours show how difficult this will be.