US President Donald Trump and Iran’s Supreme Leader Ayatollah Ali Khamenei both say that war is not on the horizon. But with no immediate prospect of talks and lacking any obvious back channels of communication, the void is filled by a history of mutual enmity. “The Iranians have for decades believed that the US wanted regime change,” said James M Dorsey, senior fellow at RSIS. “The nuclear agreement appeared to suggest that an accommodation may be possible. Trump is a return to square one.”