In 2013 or thereabouts, the Obama administration did a U-turn and accepted that Iran's right to have uranium enrichment facilities on its own soil. That's why the US negotiations with Iran about its nuclear activities, which began secretly in Oman in March 2013, ended successfully in Vienna on 14 July 2015 with agreement on the Joint Comprehensive Plan of Action (JCPOA). Without that reversal of policy, there would have been no deal.
Prior to that, the US and its allies spent nearly a decade attempting to coerce Iran into halting its enrichment programme, in recent years by applying ferocious economic sanctions which are still in place. But the attempt was unsuccessful, spectacularly so: in 2005, Iran's enrichment programme was in its infancy and no centrifuges were enriching uranium; today 19,000 centrifuges are installed and around 10,000 of them are operational.
If the US had accepted from the outset that Iran had a right to enrichment, there would have been no dispute at all about Iran's nuclear activities, let alone one that has lasted a decade - and there would have been no need for two years of intensive negotiations to resolve it with a 160-page Joint Comprehensive Plan of Action.
Iran's NPT right to enrich uranium
It is important to note that, as a 'non-nuclear-weapon' state party to the NPT, Iran has a right to uranium enrichment for civil nuclear purposes. Article IV(1) of the NPT states:
"Nothing in this Treaty shall be interpreted as affecting the inalienable right of all the Parties to the Treaty to develop research, production and use of nuclear energy for peaceful purposes without discrimination and in conformity with Articles I and II of this Treaty."
This includes the "inalienable right" to enrich uranium. We have that on the authority of the present US Secretary of State and lead negotiator, John Kerry, who told the Financial Times on 10 June 2009 that Iran had "a right to peaceful nuclear power and to enrichment in that purpose".
Other 'non-nuclear-weapon' state parties, for example, Argentina, Brazil, Germany, Japan and the Netherlands, all have uranium enrichment facilities without being accused of breaching the NPT.
So, in attempting to coerce Iran into halting its enrichment programme, the US was attempting to deny Iran its rights under the NPT, which is the primary international treaty regulating nuclear activity by states. Retaining uranium enrichment facilities on its own soil has always been Iran's bottom line and it has been prepared to endure years of wholly unjustified economic sanctions in order to defend that bottom line.
US concedes Iran's NPT right to enrichment
Now, the US has conceded the principle. However, in the Joint Comprehensive Plan of Action, the US has insisted that for the next decade and more severe restrictions must be placed on Iran's enrichment capabilities and on other aspects of its nuclear programme, with the threat that the existing sanctions will be maintained or even intensified, if Iran doesn't submit.
There is no justification for imposing such restrictions on a sovereign state. As a 'non-nuclear-weapon' party to the NPT, Iran is forbidden to acquire nuclear weapons, but the NPT places no limits on civil nuclear activity, providing it is under IAEA supervision. Iran has agreed to accept these restrictions on its nuclear activities in exchange for the lifting of economic sanctions, but they are being accepted under duress and they are an infringement of Iran's right under the NPT to unrestricted civil nuclear activity under IAEA supervision.
Having said that, Iran has now got a civil nuclear programme, the existence of which is accepted by the US and its allies, and if all goes well Iran will be free from sanctions in a matter of months. And in a decade or so, its civil nuclear programme will be free from the restrictions imposed by the US in the present agreement.
It can be guaranteed that Iran will fulfil its obligations under the agreement to the letter in order to reach that highly desirable objective - as it did with the initial Joint Plan of Action agreed in November 2013.
Iran and nuclear weapons
The stated reason for the US imposing these restrictions is to eliminate, or at least severely reduce, Iran's ability to develop nuclear weapons. To this end, the US asserts that Iran's uranium enrichment facilities must be limited so that the "the breakout time", that is, the time needed to enrich enough uranium to weapons grade for one bomb, is increased to around a year from what is said to be two or three months at present.
This assumes that Iran has the ambition to develop nuclear weapons, as Israel did many years ago, or will acquire such an ambition if the opportunity to do so arises in the future. Binyamin Netanyahu and his allies in the US Congress purport to believe that Iran has had that ambition and has been actively trying to realise it for many years. In 1992, he predicted that Iran was 3 to 5 years from being able to produce a nuclear weapon - and that the threat had to be "uprooted by an international front headed by the US". He was wrong. In a speech to the UN General Assembly on 27 September 2012, he predicted that Iran would have enough highly enriched uranium for a bomb by the following summer. He was wrong again.
The truth is that no Western intelligence service has ever managed to produce hard evidence that Iran has been trying to develop nuclear weapons. And the IAEA has never found any evidence at Iran's nuclear facilities of the diversion of nuclear material for possible military purposes. In his book Manufactured Crisis: The Untold Story of the Iran Nuclear Scare published last year, US investigative journalist Gareth Porter demonstrates meticulously that the intelligence on which assertions that Iran has or had a nuclear weapons programme was either misinterpreted or simply false.
Iran itself has repeatedly denied that it has any ambitions to develop nuclear weapons. What is more, in 2005 the Supreme Leader of Iran, Ayatollah Ali Khamenei, issued a fatwa - a religious edict - saying that "the production, stockpiling, and use of nuclear weapons are forbidden under Islam and that the Islamic Republic of Iran shall never acquire these weapons". And he has repeated this message many times since then.
Will Iran attempt to develop nuclear weapons?
Let us suppose that the agreement survives opposition in Washington and as a result Iran has established its right to enrich uranium, albeit with unjust limitations, and is free from sanctions. Let us suppose that Iran takes a decision to put this substantial achievement at risk by attempting to develop nuclear weapons, which according to the Supreme Leader are "forbidden under Islam".
To that end, it would have to attempt to enrich uranium to weapons grade. Since it has been agreed that IAEA inspectors will have continuous access to the Natanz enrichment plant, an operational change to enrich above the agreed maximum of 3.67% would soon become known to the IAEA and to the world. Very soon, therefore, irrefutable evidence would be available that Iran had breached the agreement and sanctions would be imposed - the agreement lays down a procedure for this.
That would be the end of Iran's goal of having a civil nuclear programme and being free from sanctions - and if it persisted in enriching uranium to weapons grade, it would most likely mean the destruction by military means of the nuclear infrastructure that it has devoted so much effort to build up over many years.
Iran is not going to bring that about.
Bush "angry" that Iran had no nuclear weapons programme
In a National Intelligence Estimate (NIE), produced in November 2007, the 16 US intelligence services expressed the consensus view that Iran hadn't got an active nuclear weapons programme.
The reaction of President George Bush to this good news is instructive - it made him "angry". We know this because he says so in his memoir, Decision Points (p419 Kindle edition). One might have thought that the President would have been pleased, if not jumping for joy, to receive intelligence that Iran wasn't developing nuclear weapons. After all, preventing Iran acquiring nuclear weapons was supposed to be a major objective of his foreign policy.
But instead he was "angry" - because it cut the ground from under his efforts to gain international support for what he termed "dealing with Iran". Specifically, it made it impossible for him to take military action against Iran:
"The NIE didn't just undermine diplomacy. It also tied my hands on the military side. There were many reasons I was concerned about undertaking a military strike on Iran ... . But after the NIE, how could I possibly explain using the military to destroy the nuclear facilities of a country the intelligence community said had no active nuclear weapons program?"
It seems that the Bush administration was not concerned about whether Iran had a nuclear weapons programme. What concerned it most was that the world would come to believe that Iran hadn't one - and as a result the US would no longer be able to rely on international support for maintaining pressure on Iran with the ultimate objective of overthrowing the Islamic regime.