Iran’s nuclear programme, and the world community’s reaction to it, raises the most profound questions about the strength of international law, the purpose of the United Nations and the rights of states who feel threatened by others. More prosaically, Iran’s nuclear ambitions are a potential flashpoint for war in the Middle East.  

I am concerned that in too many countries, the dangers are seen as theoretical, the time frame leisurely. Iranian Supreme Leader Khamenei says it is un-Islamic to have nuclear weapons, but Iranian actions don’t give credence to this claim. President Obama reaches out to the Islamic Republic of Iran, and his offer is dismissed either as a PR stunt or part of a crafty plot – and certainly not seen for what it was, a ground-breaking offer to change US/Iran relations.

In the last six months, engagement with Iran has become far more complex. Because the country is itself undergoing a searching examination of what it stands for – led by its own people on the streets. Because getting Iran’s leaders to abandon duplicity and opacity in respect of their nuclear intentions, and to engage in a broader rapprochement with the world, is hard to choreograph when they are divided among themselves. And because there are many Irans.  

One Iran is seen in a highly educated, entrepreneurial people, with a celebrated culture and civilisation. That Iran exists in diasporas around the world, but is also clearly present among those in Iran demanding a right to have a say in the future of their country and for that voice to be heard.

Then there is an Iran whose economy is a mess; despite sitting on the world’s second largest gas reserves it imports gas. Corruption is rife – Transparency International ranks Iran 168 out of 180 countries. According to the IMF, it has the highest brain drain in the world. This Iran restricts its educated citizenry from accessing international media for fear of what they might learn.

The regime deliberately confuses these Irans. It talks of winning the battle for technology when it launches worms into space 40 years after man went to the moon. It claims to be a defender of human rights while Iranians who assert their basic freedoms are imprisoned, beaten, shot in the streets and executed after show trials.

The resolution of the nuclear issue, and an active process to achieve its resolution matters because the two alternatives – Iran with the bomb or Iran bombed to deny it getting one – are, as President Sarkozy said, horrific.  

The IAEA has said that it is unable to verify that Iran’s nuclear programme is for exclusively peaceful purposes. Iran offers no credible explanation for producing fissile material with a clear military application, while refusing to address IAEA questions about past contacts with the nuclear black market.

The nuclear issue cuts to the future of the nuclear non-proliferation regime and the future of the Middle East. Gulf countries would likely join the nuclear bandwagon if Iran goes nuclear. Israel itself has made it crystal clear that it sees a nuclear Iran as an existential threat and would act if necessary in its self-defence. The consequences of both would be devastating.

The UN Security Council needs to take its responsibilities seriously, not just countries like the UK and China but also non-permanent members like Brazil and Turkey. The EU has stated that it will take action and countries in the region need to join us to increase the pressure.  

Sceptics say sanctions can be blunt; that Iran would never accept humiliation; and that Iran is still some way from a nuclear capability. All are true – but not the point. Sanctions can be blunt, but they can also be targeted on the financial system, on the IRGC, and on nuclear technology. The offer on the table to Iran, tabled in June 2008 and still waiting for a reply, allows it to claim the rights enjoyed by other states. But with those rights come responsibilities and Iran’s refusal to clarify its past and present activities means that there is a fundamental lack of confidence in its assertions that the programme is for peaceful purposes.

Sanctions are not a silver bullet. But that is not the test. The question is whether targeted, proportionate and reversible sanctions would add to the pressure inside this complex and teeming society for a more sensible attitude on the nuclear issue. I believe they would, that they are needed urgently, and that they can help avert one of the most dangerous flashpoints in world politics today.  

Mr Miliband is the UK’s Foreign Secretary