The new sanctions in Congress more or less coincided with the decision by EU heads of government to impose a tough set of new sanctions against the Islamic Republic (the fourth since 2006). The U.S. and EU measures are designed to increase the pressure on those in the regime who continue to defy the will of the international community. When combined with the sanctions announced by the U.N. Security Council on June 8, these steps will increase the pressure on Iran where the regime will feel it most: in the banking and energy sectors.

Iran's efforts to develop a nuclear weapon (and no one thought their uranium enrichment programme had any other purpose) is in clear breach of the Nuclear Non-Proliferation Treaty. Iran has thrown down the gauntlet at the feet of those countries that support the treaty, that believe in its aims of preventing the spread of nuclear weapons and facilitating the sharing of non-military nuclear technology. The international community cannot afford to do other than act decisively to address Iran's challenge.

The “twin track” policy remains the most effective way to achieve our aim of upholding the Non-Proliferation Treaty. It simultaneously puts pressure on the Iranian regime, while continuing to offer them a path out through negotiation. (It is worth repeating that, consistent with our obligations under the NPT, we are not trying to prevent Iran from developing a civil nuclear industry — indeed that forms part of our offer, which remains on the table, to Tehran.)

At the same time, none of the experts thought the regime was serving the Iranian people well. The vast majority of Iranians want to live in a more open society, one that respects human rights and is more at ease with itself. Many Iranians used to be proud of their (guided) democracy. But after last year's rigged election and the brutal crackdown against the opposition, they have lost their bragging rights. Iran is much less of a democracy, these days, than its neighbour Iraq.

The regime is failing its people internationally as well. The country, with its wonderfully rich history and culture, its natural resources and its hard-working and enterprising people, ought to be one of the 21st century's new, emerging economies — like its neighbour Turkey — in today's globalised world where power is more dispersed than before. But instead of shaping the new world order, Iran has backed itself into a cul-de-sac of self-destructive defiance.

The regime’s response to the international community’s demands for transparency over its nuclear programme is a clear example of that. The regime's refusal, since October last year, even to meet the E3+3 countries to discuss the enrichment programme sends a clear signal that they are not interested in ending Iran’s international isolation.

Much of the debate in the commentary pages has focused on whether sanctions will be effective in dissuading Iran from trying to develop a nuclear weapon. Our discussion on Thursday evening highlighted a different point: What would it take for the Iranian regime to focus on the needs of its people instead of courting international condemnation and sanctions by pursuing a nuclear weapons programme? I would be interested to hear your views on how the international community might encourage that.