Donald Trump’s wishful thinking, as much as Benjamin Netanyahu’s persuasion, was responsible for their illegal war on Iran. The US president wanted regime change, the eradication of Tehran’s ballistic missiles programme, to prevent it from ever building a nuclear bomb, and demilitarisation of its proxies. He announced that he would accept nothing less than unconditional surrender.

The memorandum of understanding with Iran which Mr Trump signed on Wednesday – in Versailles; perhaps not the best augury of lasting diplomatic achievement – was evidence that even he can only deny reality for so long. Given the human and broader costs of the war, a deal to end it has been long overdue. But the text exposes the sheer pointlessness of this conflict. Continuing the war might have led to “worldwide depression”, the US president said, though his concern is for the impact on the pockets of his voters rather than the poorest and hungriest globally. A disgruntled base and the looming midterms have forced him into compromises loathed by Republican hawks. Mike Pence, his former vice‑president, said that it “smacks of appeasement”.

Having squandered billions of dollars, and thousands of lives, Mr Trump is accepting less than was on offer before the conflict. His signal achievement is the opening of the strait of Hormuz, which was closed only due to the war – and the possibility that Iran could impose fees for transit in future appears to be left open. The deal pledges an end to the US blockade, the unfreezing of assets and lifting of all sanctions. Iran would be able to export oil before the nuclear dispute is resolved. Negotiations on Barack Obama’s aid-for-denuclearisation deal took 20 months; this announces a final deal within 60 days, perhaps with an extension. Postponing difficult issues is becoming a hallmark of Trumpian diplomacy. Confidence‑building is one thing. Evasion is another.

At times on Wednesday, the US president could have been briefing on Tehran’s behalf: “If other countries have [ballistic missiles], it’s a little bit unfair for them not have some,” he remarked. The war killed Iran’s supreme leader and key military figures, and pummelled its infrastructure and economy as well as its military. But Tehran has seen its escalatory tactics succeed, while the US has undermined its own credibility. Analysts suggest that the leadership is now more militarised, and arguably more hardline; parts of it may be keener to pursue nuclear weapons as the best guarantee against further attack.

Despite Mr Trump’s desperation for an exit, he threatens to “go right back to dropping bombs” should he deem it necessary. The US has twice attacked Iran while in negotiations with it. Mr Netanyahu, under intense domestic political pressure, would love to wreck the deal. Mr Trump might not keep him in check in future. Lebanon is included in the end to hostilities, but Israeli withdrawal is not stipulated and three people were killed hours after the deal was signed.

Mr Trump claimed concern for Iranian civilians before his war killed large numbers of them, destroyed essential infrastructure and intensified repression. No amount of denial can bring the schoolchildren killed by a US strike in Minab back from the dead. But the choice now is between a wholly imperfect deal or – far worse – a return to futile war. Making this agreement stick, and ideally building upon it, will require pressure, verification and accountability – not faith in a president who has already bombed first and negotiated later.