Just over a year ago, hundreds of thousands of Iranians poured on to the streets of cities across the Islamic republic to celebrate Hassan Rouhani’s landslide victory in an election viewed as a referendum on Iran’s nuclear agreement. But now many Iranians fear the country is heading towards a possible confrontation with the US as Tehran and Washington trade increasingly belligerent rhetoric. “The way things looks today, confrontation with the US may become inevitable,” said an oil businessman with links to the regime.

Mr Rouhani, one of the principal architects of the 2015 accord, promised to pursue re-engagement with the world and use the deal to lure much-needed investment to the republic. But now he has been drawn into a war of words with Donald Trump. Iranians’ concerns escalated this week after the US president warned Iran of severe “consequences” if it threatened America. Mr Trump’s toughest words yet towards the republic were apparently triggered by Mr Rouhani warning of the risk of war between the two countries. The Iranian leader was quoted as saying at the weekend that Americans should realise that establishing peace with Iran was the “mother of all peace” while conflict would be the “mother of all wars”.

The rhetoric underlines how Mr Rouhani, a pragmatist, is dispensing with his normal diplomatic language as the stand-off with the US pushes him closer to the regime hardliners that endured a humiliating defeat at the May 2017 elections. His tough stance has won him applause from the elite Revolutionary Guards and the judiciary, powerful groups at the heart of the hardliners’ camp. In contrast, pro-reform forces, which secured Mr Rouhani’s election victories in the hope that he would open up the country, are largely silent. But even reformers accept that national pride dictates that Mr Trump’s tirades against Iran makes it ever more difficult for the government to even consider talks with the US. “It is poisonous to negotiate with Trump under the circumstances,” said Hossein Marashi, a senior reformist politician. “When we face unfair attacks, we have no choice but to answer those attacks. This US approach is not sustainable and we should wait until there is a change in the next Congress or administration.”