Almost invisible (as usual) amid the various dire scenarios and hand-wringing by Western and European politicians and media pundits has been any serious, informed, considered discussion of how long it might actually take Iran to construct, test and ready any sort of nuclear fission device.
Dire predictions have Iran testing a nuclear device in as little as 1 year. Most predictions talk in terms of 3-5 years.
While it is true that every nation that has built nuclear weapons has succeeded on the first try, most of these programs relied either on obtaining information via espionage (USSR), information transfer (USA -->Great Britain,Israel --> South Africa), or secret long-term scientific and engineering programs (France, Israel, Pakistan). In some cases, the programs ran for a long time before a device was tested.
It is not clear how much detail, implementable understanding Iran has captured concerning how to build a bomb. While the basic principles of a nuclear fission explosion are well-known to high-school physics students all over the world, the devil is in the details. This can be seen by the paucity of literature available about initiator design; much of that information is still classified. An initiator is the detonation device (and one of the few uses of the element polonium). Without a properly functioning initiator, the result is a "fizz bang" with a low explosive impact and local scattering of radioactive debris. There are also a host of issues to be solved in the creation of a delivery system. Once a program to build an atomic bomb gets beyond a certain point, it becomes impossible to conceal. Testing such a device tends to shake the planet (literally) and such shakes are easy to measure. Putting the bomb on a missile requires further visible testing.
As far as anybody is saying, none of the above has occurred yet, which suggests that Iran is a lot further away from building a device than 1 year. Given that apparently uranium concentration is not even in progress on a significant scale (no U-235 or plutonium, no bomb), I find the one year scenario unbelievable. 3-5 years looks to be more likely, and we will know well in advance of its readiness, unless Iran tries to use a device without any prior testing of the weapon and it's delivery system(unlikely, but not impossible).
From a geopolitical perspective, this sort of issue was always likely to arise. Countries who want to show that they have "arrived" on the world stage are going to see nuclear weapons as a calling card to show that they have the technology and the willpower to play with the "big boys".
The attempt to restrict the spread of nuclear weapns via the Non-Proliferation Treaty is one of the more amusingly one-sided documents in recent world history - a device by which the existing members of the nuclear club have tried to get the non-members to agree to not try to join (with the exception of Israel, which, although it is generally believed to have nuclear weapons, carefully refuses to confirm or deny whether it has them). Not surprisingly, the NPT increasingly looks to have more holes in it than a kitchen colander. How any nuclear power can seriously expect to make the NPT survive in the long-term is difficult to understand.
Some of the current impetus driving Iran to create a nuclear device might be diminished if a lasting peace can be facilitated between Israel and its neighbors. However, that currently looks to be about as likely as pigs flying. Even if a Middle East peace settlement eliminates part of the Iranian motive, they still have the means; as an oil-producing country, they can use their source of energy as a bargaining chip with which to obtain reciprocal deliveries of technology and other materials which, to use the old cliche, have a "dual use". In other words, Iran is unlikely to have trouble obtaining the materials and technology to build a nuclear device as long as its oil and gas fields are still active.
This saga is going to run and run. It is my conviction that if Iran looks to be close to building a bomb, Israel will attempt to destroy the program. That action in itself will be very damaging for the Middle East, but desparate nations, like desparate people, have a habit of doing desperately stupid things (a comment that could apply to most of the countries in the Middle East at one time or another in the last 59 years). I'm glad I'm watching this from the USA, but I remain somewhat pessimistic of a good outcome to the current situation.
What is clear is that there are no easy answers to this mess. Be very wary of anybody who suggests that there is an easy answer; they either came down from the hillside with the last rainstorm, just landed from Mars, or they are stupid.