American and Iranian politicians have done well to maintain momentum in the nuclear talks between Tehran and the international community, and overcome the complicated technical obstacles that could be easily manipulated to derail the talks. The entire Iranian nuclear establishment has been working for decades in a deeply anti-American culture, in which any hint of genuine transparency and welcoming international inspection was anathema, and Israel and its pernicious allies would be delighted to force the talks to stop.

Nonetheless, the politicians have been doing good work. It was every encouraging that this week the Iranian Vice-President Ali Akbar Salehi announced the near resolution of one of the more complicated issues, when he said that Iran will redesign its Arak heavy water reactor to greatly limit the amount of plutonium it can produce. This is a major concession from Iran, which comes in good time to beat the July 20 deadline for a final deal to limit the country’s ability to build nuclear arms in exchange for ending the crippling economic sanctions it faces.

The concession also comes at time when the US is seeking to ban the Iranian ambassador to the United Nations, in a controversial legislation that has been rushed through Congress and has been partially disowned by President Barack Obama, who said that he would not accept any limit to his executive authority. Despite the willingness to concede in some areas, Iran is not giving in to the wilder demands of the Americans. It has refused to change the Arak heavy water reactor into a light water reactor, on the basis that heavy water is needed to produce radioisotopes for the treatment of patients while it already manufactures light water in Bushehr to help generate electricity. After the initial deal was reached last November, Iran stopped enriching uranium to 20 per cent, and agreed to dilute half the uranium it has already enriched from 20 per cent to 5 per cent, and convert most of its stocks of 20 per cent enriched uranium into oxide, which is hard to use for making nuclear bombs.