The US military say that a military strike may only delay Iran from getting a nuclear weapon.
By Kim Ghattas
BBC News, Washington
If Iran decides to go for nuclear weapons, the US may not be able to permanently stop this from happening unless it is willing to occupy the country.
This is the candid conclusion of one US general testifying in front of the Senate but one that seems to have gone mostly unnoticed amid a flurry of statements on Iran over the past few days in Washington.
Gen James Cartwright, one of America's top uniformed officers, slowly edged towards that conclusion during a Senate testimony last week, underscoring the difficult choices facing the Obama administration as it weighs what do about Iran.
Gen Cartwright agreed a military strike would only delay Iran
Since the US would probably be extremely apprehensive about even considering putting boots on the ground in Iran, the statement raises a key question - while the Obama administration publicly maintains that it will not allow Iran's current leaders to acquire nuclear weapons, is it privately discussing how to live with a nuclear Iran?
The military is averse to any action against Iran and Adm Mike Mullen, the chairman of the Joint Chiefs of Staff, said a military strike would be 'his last option" and has warned of the unintended consequences of such a strike.
One of those consequences could be a boost in the life expentancy of the Iranian leadership.
If Iran comes under attack from the outside, Iranians will likely rally around their leaders or be forced to do so.
This would put an end to any internal dissent and delay the prospect of internal pressure for change. After all, a different Iranian leadership that cooperates more with the international community is another way of allaying concerns about Iranian nuclear ambitions.
But during the Senate testimony, which also featured the state department's No 3 official, William Burns, the senators questioning the panel also established that UN sanctions would probably not be tough enough to really have an impact on Tehran.
Senator Jack Reed, a Democrat from Rhode Island, then asked Gen Cartwright whether the "military approach was a magic wand".
Gen Cartwright, the vice-chairman of the Joint Chiefs of Staff, acknowledged it was not, adding that military action alone was unlikely to be decisive.
Senator Reed prodded further, getting the general to agree that a military strike would only delay Iran obtaining a nuclear weapon if Tehran decided to go nuclear.
The senator then went further, asking whether the only way to absolutely end any potential Iranian nuclear weapon programme "was to physically occupy their country and disestablish their nuclear facilities?"
The general answered: "Absent some other unknown calculus that would go on, that's a fair conclusion."
Graham Allison from the Belfer Center for Science and International Affairs at the Harvard Kennedy School said it was very difficult to stop a state determined to get the nuclear bomb if they decided they wanted it.
"Iran has lost its nuclear virginity, and it's a fact that can't be erased," said Mr Allison.
A lot of the focus in recent days has been on a leaked memo sent by Defence Secretary Robert Gates, which apparently lays out what steps to take against Iran's nuclear programme if it ignores international sanctions.
The memo was described by the New York Times as a wake up call for the administration, but Mr Gates said it was meant "to contribute to an orderly and timely decision process making".
Either way, the Obama administration is considering the options it has if sanctions do not have the intended impact. But critics say that is not enough.
'So far, no action'
"We have not done anything that would in any way be viewed effective. I didn't need a secret memo from Mr Gates to ascertain that," said Republican Senator John McCain on Fox News over the weekend.
Senator McCain was also on the Senate armed services committee questioning Gen Cartwright.
"The list goes on and on of the threats that we have made to the Iranians and so far no action" said Senator McCain.
"George Schultz, my favourite secretary of state in all the world, once said his marine drill instructor told him, never point a gun at somebody unless you're ready to pull the trigger. We keep pointing the gun. We haven't pulled a single trigger yet, and it's about time that we did."
Senator McCain was probably also speaking figuratively about crippling sanctions.
"The ripple effects in the region of a military strike against Iran would be ugly," said one senior US official speaking on the condition of anonymity because of the sensitivity of the issue.
But he added that the longer it took to put sanctions in place, the more the risk of a military strike increased.
"The closer you get to the end of 2010, the temptation to act gets greater," said the official, who seemed to implicitly indicate it was Israel that would mostly be tempted to act.
This would still only delay any Iranian plans to pursue nuclear weapons.
Ideally, the Obama administration would like to convince Tehran that a nuclear weapon will not make it more powerful or more secure.
But without a change inside Iran, that argument is unlikely to have much weight because Iran does believe that its nuclear ambitions give it added clout in the region.
"If the international community was prepared to impose crippling sanctions, embargoing imports of gasoline and exports of oil, if it strangles Iran - Iran might recalculate," said Mr Allison from the Belfer Center.
"This is a regime that has survival at the top of its list. But imposing such sanctions without the support of Russia and China is impossible."
So with the US neither able to impose crippling sanctions nor really eager to take the tough military action needed to permanently disable Iran's nuclear facilities, Washington's only options seem to be to either accept a nuclear Iran or find ways to continuously disrupt and slow down Iran's nuclear ambitions.