Ali Larijani, the speaker of the Iranian parliament, said yesterday that Tehran had a specific plan of action if the United States withdrew from the nuclear pact and that Washington would regret any such decision, the Interfax news agency reported. Larijani made the statement in St Petersburg where he was taking part in a parliamentary forum.

Trump caused alarm across the Atlantic with a belligerent speech on Friday in which he stopped short of pulling out of the agreement but warned he could do so at any time, restating his belief that the deal was letting Iran off the hook. He left it to the US Congress to decide whether to reimpose sanctions that were lifted in return for Tehran abandoning its nuclear ambitions. Trump is a fierce critic of the 2015 accord, which he has called "the worst deal ever", and he is expected to announce that he is "decertifying" Iran's compliance with it.The U.N.'s atomic agency has repeatedly certified that Iran is sticking to its technical requirements under the accord, but Trump has insisted that the "fanatical regime" in Tehran is not living up to the "spirit" of the deal. The nuclear deal is supported by Washington's European allies Britain, France and Germany, as well as by Russia and China, all of which say Iran has complied so far.