Just one in four Americans believes US President Donald Trump’s war with Iran was worth its costs and a majority worry that a truce with Tehran is unlikely to last, a Reuters/Ipsos poll finds.

The five-day poll, which closed on Monday, also showed the war weighing heavily on Trump’s popularity, with his approval rating dropping to 34 per cent, a return to the lowest level of the Republican’s second term that was last touched in an April survey.

Only 23pc of Americans including just half of Republicans think the US is now in a stronger position with Iran compared with its position before the war, the poll found. Some 35pc of respondents think it is in a weaker position. The rest said they were not sure or that the US position was about the same as before.