US: Despite denials that possible military action against Iran is being discussed at the highest levels, it is almost certain that planning is beyond the conceptual stage, writes Rory Miller
The potential destabilising effect of a US attack on Iran cannot be underestimated.
Nor, however, should one ignore the possibility that in the final account, Washington, and even a number of its EU allies, may conclude that allowing Iran to gain a nuclear bomb is more dangerous to regional and global instability than taking such military action.
So what are the potential military options?
First of all, although reports of unofficial war-gaming in the US have shown that a successful pre-emptive strike would need to take out approximately 300 targets (including well-known nuclear facilities, chemical and biological production installations, ballistic missile batteries, major airfields and command and communication centres), included on this list is a much smaller number of high value targets, perhaps a dozen or so, that could be given priority.
These include the nuclear reactor under construction in Bushehr, the enrichment facilities at Natanz, the heavy water facilities at Arak, the uranium conversion installations at Isfahan and a number of research sites which are believed to be involved in the weaponisation of nuclear warheads.
With the exception of the uranium-enrichment sites at Natanz, much of which is both built underground and hardened, most of these targets should be relatively easy to destroy as they cannot be moved, hidden or properly protected against air power.
Even if, as is likely, Iran has dispersed its nuclear programme and is prepared to defend various key sites, US air assets based in Iraq and on aircraft carriers in the Gulf provide the capability to neutralise most of these targets.
A combination of air and sea-launched missiles would be used as well as gravity bombs including, in the latter instance, conventional bunker-busters.
In late 2004 Iran deployed a brigade-size rapid deployment force to respond to any military attack on the nuclear programme.
Even if US planners are not aware of significant parts of the Iranian programme, the successful destruction of all targeted sites would only have a partial and temporary impact on Iran's broader proliferation efforts.
However, the US may believe that any resort to force may act as a deterrent to Iran and may also buy valuable time.
The case of Israel's destruction of Iraq's Osirak reactor in 1981 is instructive. The attack did not prevent Saddam Hussein from attempting to reconstitute his nuclear programme, but it made them far more difficult.
Thus, American planners, faced with worst-case scenarios that put Iranian nuclear weapons only 24 months away, may prefer to counter the immediate danger by way of a military assault and then exploit a more generous timeframe to work to derail the longer-term threat.
Moreover, while the US has encountered severe problems in containing the insurgency in Iraq, an air strike against Iranian targets would be the kind of military operation at which it excels.
As such, to argue that the military option does not exist is not correct. Rather, the main arguments against the military option are political and economic in nature. Iranian officials have consistently warned that any attack would be "a huge irreparable mistake", and have promised that US interests "will be easily damaged" following such an action.
There is no doubt that Iran has the capability to target the US or its allies in retaliation, either directly or indirectly through proxy groups such as Hizbullah in Lebanon.
However, it is also likely that US naval forces in the Gulf and the Straits of Hormuz could neutralise any larger conventional Iranian military reprisal in the region.
A potentially bigger problem is the response of the international community, in particular the Arab and Muslim world, Russia and China, and vocal opponents of military action inside the EU, to any military action.
However, while such nations are likely to condemn any US attack publicly, it is also true that many, including Turkey, Saudi Arabia, and the Gulf kingdoms, if presented with a fait accompli, will be relieved by the neutralisation or temporary slowdown of the Iranian nuclear programme.
Dr Rory Miller is a senior lecturer in Mediterranean studies at King's College London