The very real danger of a nuclear Iran.

There are few more frightening prospects than a nuclear war. Nuclear weapons have only been used twice in history and both were used to end wars that had already ravaged much of the world and left a generation of young men on the fields of battle to die in a heroic way, far away from home.
Iran wants to use nuclear weaponry to start a war, not to end it. They've made claims that there technology is for peaceful purposes but these claims have been debunked by anyone with a knowledge of nuclear technology.
The program was launched in the 1950's, ironically, with the help of the United States but since the election and rise of President Mahmoud Ahmedinejad it has perverted the course that the United States originally wanted it to take.
A nuclear Iran doesn't only threaten Israel but also the Europeans and the rest of the Arab world that finds itself at odds with Iran such as Turkey. Very recently the French government told the world to 'prepare for war' in regards to Iran's nuclear ambitions.
The fears that people have of a nuclear Iran are very real. It's well known that Iran funds various terrorist groups throughout the world, Hezbollah for instance received weapons and support during their 2006 war with Israel, and Iran also supports the terrorists in Iraq.
What would happen when Iran creates this nuclear weapon, who will they target first? US troops in Iraq? Turkey? Israel perhaps?
This will in turn lead retaliatory attacks on Iranian facilities and towns, the death toll will be enormous and will easily reach into the hundreds of thousands, if not millions.
There are two options at our disposal.

-Diplomacy.
This could possibly work, by forcing Iran into a corner and shutting down their nuclear activities then the problem will be solved. This would only work if the United Nations can impose harsh enough measures to make sure that the Iranians understand that the only way out of the hole they've dug is to give up their ambition of a nuclear bomb.

-Surgical Air Strikes and Commando Raids.
The Iranians have made sure that their reactors aren't going down without a fight. They're extraordinarily well protected and underground. To fully destroy them Special Forces would have to enter the facilities and fight their way to the core before detonating explosives and escaping before the airforce bombs the remaining facilities. This will lead to deaths on both sides and will officially lead to international condemnation (but behind closed doors there will be thousands of sighs of relief)

-Do Nothing.
Best Case Scenario for this would be only a few thousand people dead from nuclear fall-out. More likely the bomb will be aimed at Israel which could leave up to between three to five million people dead not to mention the destruction of the Western Wall, Dome of the Rock and Church of the Nativity. This in turn could lead to religious turmoil throughout the rest of the world with retaliatory attacks against Iranian and Muslim communities.

Diplomacy is the idea solution to this problem but the radical and unstable regime of Ahmedinejad makes it less and less likely. As Iran enters the point of no return i'm quite sure that many jets will be fueled and many guns will be loaded. Another preemptive strike perhaps, ending lives to save many, many more.