After twelve years of on-off negotiations, there is now a possibility of a ground-breaking deal between the international community and Iran on its nuclear programme.

Iran, like other nations signed up to the “Non-Proliferation Treaty” (NPT), has an unquestionable right to a civil nuclear programme – but not to a nuclear weapons’ programme.

Against predictions in the early sixties that there would be 30 states with nuclear weapons, there are nine – the five Permanent Members of the Security Council, authorised by the NPT, plus India, Pakistan, North Korea, and Israel, all outside the NPT.

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In 2002 strong suspicions emerged that Iran was concealing a nuclear weapons’ programme – though Iran has always denied this. Negotiations, between 2003 and 2005, failed under pressure from hard-liners in Tehran and Washington. Sanctions were imposed. The Iranian people had to endure a dismal eight years under President Ahmadinejad.

The election in mid-2013 of reformist Hassan Rouhani as Iranian President, combined with a more forward foreign policy of US President Obama, saw talks resume.

An interim deal was reached in November 2013. There’s been some sanctions relief. But, as ever with tough international negotiations, it’s the really tricky issues which have been left till last – like how much uranium the Iranians should be permitted to produce, at what strength, with what safeguards, and what the Iranians get back in return.

To make matters even tougher for President Obama in comes Israeli Prime Minister Binyamin Netanyahu.

In a remarkable breach of diplomatic protocol he’s denounced the likely outcome of the negotiations, claiming that it would represent a “very bad deal”. So bitter have feelings become in Washington about Mr Netanyahu that the Democrat House leader said his speech was an insult to the intelligence of the United States.

The US intelligence community have, consistently since 2007, assessed that Iran stopped pursuing an active nuclear weapons’ programme in 2003 – most likely because of the unprecedented unity shown by the international community. But if there is no deal that unity will start to dissolve. First the Chinese and the Russians, then many EU countries, will not be willing to dance to Mr Netanyahu, and the US Republicans’ tune. US sanctions may remain, but those of the EU and UN may well start to erode.

Iran will have signed up to no new obligations. The world will become that bit riskier.

Mr Netanyahu should be careful what he wishes for.