“This is a dangerous game,” an Iranian foreign ministry official warned on Friday. He was urging the UK to release the Iranian tanker which the British navy helped authorities in Gibraltar to seize last week. But the context, as he made clear, is the intensifying struggle between Washington and Tehran, in which the main players appear overconfident they know the rules and understand the stakes, while minor players fret about outcomes they have limited power to change.

Mohamed ElBaradei, who headed the UN nuclear watchdog in the run-up to the invasion of Iraq, has offered one of the sharpest warnings of the potential consequences: “All that I hear basically [brings] to mind the days before the Iraq war,” he told the BBC. The Iranian regime’s record at home and in the region is a grim one. But this crisis was created by the US president’s determination to destroy an international nuclear deal – which Iran was abiding by – and throttle the economy. It cornered Tehran and empowered its hardliners, who seized on the proof that America could never be trusted.