I think that if Iran detonates anuclear weapon in Israel or more so in the USA it will be quite apparent that we should have done what it takes. I have zero BDS. To answer you more specifically, the nuclear facilities needed to be taken out in joint US/Israel airstrikes. If Iran was going to respond with missiles against our fleet and troops and with an attempted blockade of the Gulf, then we will need to combat and defeat the Iranian navy and air forces as well. Whether we would need to invade Iran is another issue, Iran might or might not attack into Iraq, and we have more than enough forces in the region to defeat Iran. Obviously the uSA can defeat Iran if it has to.
And I think we needed to, indeed Obama is about to face exactly this challenge of a nuclear Iran. Fair share has nothing to do with it, this involves our survival. And Iran is a far more credible threat than Iraq was.
I hope I have explained my thinking, which relates to our security, not to Bush Obama or any politician.
Fair enough.