Might I suggest nothing other than political expediency.

Under the Sha, America was aiding and abetting Iran to build a nuclear powered infrastructure.

1970sThe Shah approved plans to construct, with U.S. help, up to 23 nuclear power stations by 2000.[45] In March 1974, the Shah envisioned a time when the world's oil supply would run out, and declared, "Petroleum is a noble material, much too valuable to burn ... We envision producing, as soon as possible, 23,000 megawatts of electricity using nuclear plants."[46]

http://en.wikipedia.org/wiki/Nuclear_program_of_Iran

That reasoning has more strength today than it ever did before.

No matter where you delve, no definitive evidence that Iran is building a nuclear weapon can be found, it's all conjecture. If anything the evidence available is proof Iran is not pursuing nuclear weapons.

BBC today:

The head of the Israeli military has said he does not think Iran will develop nuclear weapons.

http://www.bbc.co.uk/news/world-middle-east-17837768

No intelligence agencies as far as I'm aware has provided evidence to show Iran is doing anything illegal outside of that permitted under its membership of the NPT,

A lot of fuss was made when Iran declared it had enriched Uranium to 20%. 20% is rated as low enrichment by the IAEA. The horror struck myth makers declared this was evidence Iran was building a bomb and enrichment to this stage was proof of such a programme.

NPT:

Treaty on the Non-Proliferation of Nuclear Weapons [NPT]
Provisions
The Treaty on the Non-Proliferation of Nuclear Weapons, also referred to as the Nuclear Non-Proliferation Treaty (NPT), obligates the five acknowledged nuclear-weapon states (the United States, Russian Federation, United Kingdom, France, and China) not to transfer nuclear weapons, other nuclear explosive devices, or their technology to any non-nuclear-weapon state. Nuclear weapon States Parties are also obligated, under Article VI, .to "pursue negotiations in good faith on effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament, and on a treaty on general and complete disarmament under strict and effective international control." Non-nuclear-weapon States Parties undertake not to acquire or produce nuclear weapons or nuclear explosive devices. They are required also to accept safeguards to detect diversions of nuclear materials from peaceful activities, such as power generation, to the production of nuclear weapons or other nuclear explosive devices. This must be done in accordance with an individual safeguards agreement, concluded between each non-nuclear-weapon State Party and the International Atomic Energy Agency (IAEA). Under these agreements, all nuclear materials in peaceful civil facilities under the jurisdiction of the state must be declared to the IAEA, whose inspectors have routine access to the facilities for periodic monitoring and inspections. If information from routine inspections is not sufficient to fulfil its responsibilities, the IAEA may consult with the state regarding special inspections within or outside declared facilities.

Only one country has shown a willingness to use nuclear weapons, that country, along with its main nuclear adversary, can be charged with dragging its heels in meeting its obligations as a member of the NPT.

It is not illegal for Iran to have the knowledge and capability to make a nuclear bomb without actually doing so.

The nonsensical sanctions imposed on Iran should be removed and Iran allowed to flourish, if its regime is to be changed it should be done from within and not something imposed from outside forces.

One myth supporting another:

Israel's Deputy Prime Minister Admits Ahmadinejad Never Said Israel Should Be 'Wiped Off the Face of the Map'

http://www.commondreams.org/headline/2012/04/18-2

What's it all about?


Regards

Tony