Nigel Farage has said he fears Donald Trump will "aggressively" continue his war with Iran after his "disaster" in the US midterm elections.
The Reform UK leader said the US president was still a friend, but accused him of having "broke a promise" to the American electorate by launching the war.
The war in Iran, which the US began in February 2026, weighed heavily in the midterm election results earlier this week in which the Democrats swept Trump's Republicans out of power in Congress.
Farage, who had initially urged people to support the war, said that following the election results he worried Trump would respond with more strikes on Iran.
Asked how he thinks President Trump will respond, Farage told broadcasters on Thursday: "I suppose I worry that the President will continue aggressively attacking Iran.
"That worries me because that would have even more serious implications for the price of oil, for inflation, for the whole western world".
He acknowledged he had initially supported the war but stressed he "never supported endless war".
Asked if the war was a mistake, he said: "There's no question about it."
The US president had "always kept his promises," added Farage, but "in this case, he said no more foreign wars and here we are in month eight of a war with no sign of ending."
"That and the resulting fuel prices are what in the end has done the damage."
Trump acknowledged on Tuesday the poor results for Republican congressional candidates were partly due to the war and the related surge in oil prices across global markets, including in the US and UK.
But he insisted he did not regret launching a joint attack with Israel on Iran.
In recent weeks, Trump has warned the US and Israel could return to all-out war after the midterms if a deal to end the conflict cannot be reached with Iran.
There have been various warnings , including from politicians in the UK, that Trump may now step up his attacks on Iran but Farage's criticism was more vocal than many have been.
Prime Minister Andy Burnham said earlier this week he hoped the midterm results meant there was an "opportunity now to unite around the issue that is affecting us all, and that's the cost of living".
Farage said he had not spoken to Trump since the midterms but described it as a "complete wipeout" and "an absolute shellacking" for the Republicans.
"Trump has had an amazing career - he has beaten the pollsters, he has gone way beyond expectations," he added.
"This was his last big election and they all say, that all political careers end in failure."
His comments came at an event to announce Reform's first defence spokesperson, after the party was criticised for not having one.
Angus MacIntyre said he had stood down from a 40-year military career, including as a Wing Commander in the Royal Air Force (RAF), to take on the role.
MacIntyre pledged in a speech to end prosecutions of serving military personnel and veterans within the first 100 days of a Reform government.
Defence Secretary Wes Streeting and Tory leader Kemi Badenoch had criticised Reform for lacking a defence spokesperson despite having dedicated posts for immigration, the economy and education.
Farage said MacIntyre would form part of "a team we will build to represent us" on the issues of defence, security and cybersecurity.
