British Chancellor Rachel Reeves has sharply criticised US President Donald Trump's decision to go to war with Iran, calling it a "mistake" that has destabilised the global economy, hurt living standards, and left the world less safe than before hostilities began. Speaking at an event in Washington during the International Monetary Fund's spring meetings, Reeves said she was "not convinced this conflict has made the world a safer place" and called for urgent de-escalation as the priority for both governments.

Reeves directed pointed criticism at the White House on its home turf, arguing that Trump abandoned a functioning diplomatic channel when he broke off formal talks with Iran and launched airstrikes in late February. She noted that the Strait of Hormuz — the narrow waterway between the Arabian Peninsula and Iran through which a significant share of the world's oil exports pass — was open before the conflict began, and questioned whether renewed efforts to reopen it represented any meaningful gain. "We had the waterway open a few weeks ago," she said. She also challenged the logic of military action as a means of preventing Iran from developing nuclear weapons, arguing that diplomacy remained the more effective path. Eleven finance ministers, including those from Australia, Japan, Spain and Sweden, issued a joint statement alongside Reeves urging safe passage of energy supplies from the Gulf and calling on nations to avoid "unnecessary trade restrictions" — a thinly veiled rebuke of Washington's approach.

At home, Prime Minister Keir Starmer told the House of Commons he would not change course despite intense pressure from Trump. "I'm not going to yield — it is not in our national interest to join this war," Starmer said during Prime Minister's Questions. His stance has drawn increasingly personal attacks from Trump, who told Sky News that when the US asked Britain for help "they were not there," and suggested the bilateral tariff agreement reached last May — which reduced import taxes on British cars, steel and aluminium — "can always be changed." Starmer said such threats would not alter his position.

The exchange marks a significant strain on the so-called special relationship between the two countries. The IMF warned this week that a further escalation in the Iran conflict could trigger a global recession, with the UK — as a net importer of gas — among the most exposed of the G7 economies. The fund cut its UK growth forecast for this year to 0.8%, down from 1.3% before hostilities began. IMF Managing Director Kristalina Georgieva said the war represented a "very large" shock to the global economy and called for it to end as soon as possible.

Despite the tensions, both sides have tried to preserve appearances of a working relationship. Reeves met US Treasury Secretary Scott Bessent on the sidelines of the IMF meetings, framing the disagreement as one between allies who can "speak their truth" to each other. Starmer is due to meet French President Emmanuel Macron in Paris on Friday to discuss protecting shipping through the Strait of Hormuz, with Reeves indicating the UK is willing to contribute to safeguarding oil supplies once a "proper ceasefire" is in place. Trump, for his part, said the planned state visit by King Charles and Queen Camilla later in April would proceed without difficulty.