Many analysts maintain that the renewed US sanctions against Iran will be ineffective. The argument, even among some Trump supporters, is that the bumbling Barack Obama threw away a unique opportunity to force the ayatollahs to abandon their regional aggression as well as their development of nuclear weapons. The 2015 nuclear deal failed utterly to address Iran’s malign influence throughout the Middle East and further afield. It focused only on Tehran’s nuclear ambitions and even there it failed. The ayatollahs were obliged to accept only a moratorium on their nuclear program, which they very quickly began to disregard.

Obama’s removal of sanctions allowed Iran to relocate billions of dollars frozen in international accounts to countries such as Russia and China which were unlikely to implement any new sanctions. Moreover, Tehran set about luring international companies to undertake essential reconstruction of its decayed infrastructure, particularly in the oil industry. The plan was that even if US corporations were once again obliged to pull out of new lucrative deals, European as well as Chinese and Russian enterprises would step forward to fill the gap. Thus, at first glance, the long-overdue tough stance taken by President Trump was likely doomed to failure.

However, it is not quite working out this way. For a start, despite the EU’s refusal to follow Washington’s lead and its attempts to indemnify European companies from any punitive action the US might take, many of these businesses have nevertheless pulled back from alluring contracts so recently inked with Tehran. Moreover, the key SWIFT international payments network has resisted considerable pressure from Brussels, where it is also based, and has announced it will suspend clearing with some, though not yet all Iranian banks. This is going to make it a great deal harder for Tehran to move funds.

As yet, Trump has not tried to shut down all Iranian oil exports. His administration has granted exemptions to China, India, Italy, Greece, Japan, South Korea, Taiwan and Turkey, the first two of whom are now Iran’s biggest trading partners. China and Turkey might refuse to stop buying Iranian oil but such a rejection would surely exacerbate Washington’s trade confrontation with Beijing and would probably serve to isolate Ankara, driving President Recep Tayyip Erdogan even further into the dangerous arms of Russia’s president Vladimir Putin. India could also seek to defy Trump, but as itself a nuclear power, it has a responsibility and even an interest in seeking to stop the proliferation of such terrible weaponry, especially in the hands of leaders as unreliable and manic as the ayatollahs.

And in one crucial respect, the Iranian leadership is itself already reinforcing Trump’s hardline position. It is not simply that Iran has suffered badly this year from drought, which has seen a collapse in agricultural yields; it has also produced almost 40 years of incompetent and venal rule. The 1979 revolution that brought Iran’s theocracy to power has been characterized by economic and social failure. Even in the four years since the end of international sanctions, the economy has struggled. The currency has collapsed, along with the standard of living for all but the favored elite clustered around the trough of corruption and payola in Tehran. By embroiling the country in expensive foreign adventures while neglecting its own people, the regime has lost all legitimacy and its right to govern.