Like rotogun said, a premptive nuclear strike on Iran is not needed. Besides what would be the message put out by stopping nuclear ambitions with nuclear force? Not to mention the repurctions that would happen throughout the world and not to mention that fully justified rage the the muslims throughout the world would express.
This problem needs to be solved diplomatically and if not that way then militarily but with conventional forces. Too bad Russia and China won't even agree to an economic embargo. The Chinese ambassador to the UN said something to the extent of "this situation is delicate and we don't want to make it more complicated" in other words "we need their oil and don't think it our problem, scew you"