Since the revolution that toppled the Shah in 1979, Iran has been the greatest destabilising influence in the Middle East. As a Shia power in a predominantly Sunni region, its transformation into a theocratic state was always going to be problematic. The West’s response was to prop up Sunni Arab counterweights, notably Iraq under Saddam Hussein which then fought an eight-year war with Iran in which 500,000 people died only to end in stalemate.
The Americans, backed by the UK, then removed Hussein, who had been the bulwark against Tehran’s regional hegemony, only to reinvigorate it. Iran embarked on a nuclear weapons programme, threatening its Sunni neighbours and Israel, which the West sought to restrict to peaceful energy development. That agreement was torn up by Donald Trump partly because it was a bad deal but also because it was a legacy of his predecessor, Barack Obama, that he was keen to disavow.
However, Mr Trump did not put any alternative plan in place. His isolationist inclinations have left a vacuum in the Middle East which is being filled by other players like Russia and Turkey but, above all, by Iran. Far from being marginalised, an analysis by the International Institute for Strategic Studies suggests Iran is now the foremost power in the region, successfully prosecuting asymmetrical warfare through non-state partners like Hezbollah in Syria and Lebanon, the Houthis in Yemen and Shia supporters in Iraq while keeping attacks on itself to a minimum.
The policy to contain Iran has been a failure. Threats have not worked, because they have not been followed up with action, and neither have sanctions. Does Mr Trump have another plan?