As for Iran's missile capabilities? I believe that what missiles they have were, at least in part, provided by North Korea, however North Korea chooses to use their own technology. In any case, the capability is far behind other nations. The answer is, of course, the Reagan program for space defenses against all potential foes--not focusing on one of many potential foes.
I have dealt with this situation in Pseudo Pragmatism--Political Folly.
The issue is not whether we have adequate defense. Of course, we must have adequate defense. What we must not do is waste our resources in fights that undermine our historic credibility, while undermining our eventual ability to deal with far more serious potential threats.
There is another aspect of this, I have not addressed before this moment; and that is this:
Obama is an amoral opportunist. He is undoubtedly considering the classic maneuver of the demagogue in power, seeking to enhance his power; and that is a sudden crisis, that he is able to control. The almost hysterical focus of certain Republican candidates on Iran, is pure opportunity for Obama. He can pick an incident--perhaps solely of his own creation--and attack Iran, putting many Republicans into a real quandry, trapped by their own rhetoric.
I do not know whether Obama's Islamic background is Shiite of Sunni. If the latter, this ploy would be all the more appealing to Obama.
William Flax