‘And by the way,’ Donald Trump said to Hillary Clinton in last night’s debate, ‘another one powerful is the worst deal I think I’ve ever seen negotiated that you started is the Iran deal.’ His view on the Iranian nuclear deal, and the nuclear weapons situation in general, hasn’t changed much since he spoke with two New York Times reporters in March. Not surprisingly he revealed an abominable ignorance of the subject.

He views the deal as a financial arrangement in which the US ‘gave’ the Iranians billions of dollars and got nothing in return. He would have walked out until he got a better deal. He ignored the fact that the US returned to the Iranians their money which we had confiscated. He complained that the Iranians took their aeroplane buying business to non-US companies until it was pointed out to him that companies like Boeing were forbidden by law to sell their planes to Iran. This embargo was lifted just days ago. He also said that we do not even know that America’s deterrent weapons would work. We also do not know if the sun will rise tomorrow but I wouldn’t bet against it.

Enough time has passed that we can now see how well the agreement is working. On 8 September the IAEA issued a report and I think it is fair to say that it is working quite well with some concerns around the margins. One thing on which there has been no progress is for the Iranians to reveal what the IAEA calls the ‘past military dimensions’ of their programme. The Iranians are adamant that any military work stopped years ago, but they will not allow any interviews with their scientists. I am persuaded that they have the designs for nuclear weapons. They have very competent physicists, and it is worth remembering that Pakistan’s successful nuclear devices were designed by half a dozen physicists, using computers less powerful than a modern laptop. But so long as the Iranians do not have fissile material, any designs they may have are more or less academic, and the IAEA appears to have been successful so far at keeping fissile material out of Iran’s hands.

The deal allows them to have at any one time only 300 kilogrammes of lightly enriched uranium. The IAEA says that the Iranians have met this obligation, though David Albright and Andrea Stricker of the Institute for Science and International Security note that the Iranians might have found ways of concealing some of their material from the IAEA. But one thing appears certain and that is that there is no highly enriched uranium in Iran. That is what matters. The Iranians are also limited in the amount of heavy water they can maintain:130 metric tonnes. Albright and Stricker say there may be some heavy water under Iranian control in Oman. The IAEA report does not mention this. Heavy water is used as a ‘moderator’ in plutonium producing reactors. There was one at Arak and the Iranians, the IAEA informs us, have not pursued its construction.

The bottom line seems quite simple to me. Before the agreement, the Iranians were only a few months from having enough fissile material to make a bomb. Now they are some years. Despite Trump’s misinformed rhetoric this was never a business deal. It was a security deal and the US is now much more secure. Trump argued for countries like Japan and South Korea to construct their own nuclear weapons. He seems to have no understanding of the power of these weapons and has not stated clearly when he would order their use if he was ever elected president.