It doesnt matter if we strike their nuclear facilities.... by the time we do, it will be too late, in my opinion anyway. I believe this due to the following:
Iran has now restarted conversion of uranium at its Isfahan plant. Before its suspension, it created 37 tons of UF4 gas. Once this UF4 is converted to UF6, Iran will have enough feedstock for their centrifuges to create 5 bombs worth of fissile material.
Once they have the feedstock, they are a defacto nuclear power.
They can take that feedstock and enrich it anywhere in the country. They dont need Natanz or any other nuclear installation after they possess the feedstock. If we bomb them, as long as they keep that feedstock material safe, they can always build more centerfuges. The Natanz enrichment plant is an empty building, waiting to receive installation of Iran's centrifuges. I dont see how blowing up an empty building would benefit us.
They can build new centrifuges, start a 3000 to 4000 centrifuge cascade at some secret location, and begin enriching the uranium. They will most likely want to use a place where they can use civilians as a shield so we wont bomb that site also. They could put 4000 centrifuges in the basement of a high school or a holy site and enrich the uranium there.
Not likely anyone is going to blow up school children... and in all likelihood, we would never know where to look for the new centrifuges anyway. Iran is very good at hiding things. They hid their program for 18 years. And if they get bombed, you better belive they are going to go into untra stealth mode with their program. They will kick out the IAEA and their inspectors and take their entire program underground.
In other words, if we dont act now to stop Iran from turning that UF4 gas into UF6, the nuclear genie has already left the bottle.
Iran can then enrich that material whenever it wants, wherever it wants in total secrecy. Bombing them after they turn this UF4 to UF6 would only prevent them from being able to produce more feedstock to create even more bombs. But they would still have that 5 bombs worth, which is 5 bombs too many.
By the time we are done with the BS diplomacy and going through the UN hoops, Iran will probably possess anywhere from 10 to 15 bombs worth of UF6. Plenty enough to start them off with a decent size arsenal. It will probably take anywhere from 3 to 5 years to completely enrich all this material using 3000 centrifuges.
They can then rebuild what we bombed under the protection of their new "nuclear deterrent" as North Korea would say.
On a side note:
A new report released by the National Council for Resistance in Iran states they have new information that Iran has a hidden location already set to go with 4000 centrifuges in place. This is the same group that revealed the existance of Iran's Natanz and Arak nuclear installations. This could save them a great deal of time seeing as they would not have to make centrifuges from scratch if it were true.