Rachel Reeves had an angry exchange with her US counterpart, Scott Bessent, in Washington last month over the war in Iran, sources have said, in the latest sign of the deepening tensions between the two countries. The chancellor and the US treasury secretary argued in person during the spring meetings of the International Monetary Fund, according to people briefed on the exchange, confirming a story first reported by the Financial Times. The row centred on Reeves’s criticisms over the Iran conflict, which she made in public before the meetings began, triggering an angry backlash from some in the Trump administration. Criticisms by Reeves and the prime minister, Keir Starmer, have caused the biggest rift in US-UK relations for decades, with the US president, Donald Trump, threatening to rip up a trade deal and to recognise Argentina’s claims to the Falkland Islands in response.…