Don't assume we can only briefly delay Iran's nuclear programs if we really hit Iran hard in a multi-week campaign.
Remember, when we hit Iraq's WMD infrastructure in 1998's Operation Desert Fox, we assumed we could only delay Saddam for a year, if memory serves me. We seem to have done far more harm in the four-day assault.
But I'm on record as believing that buying even a year of time is worth the risks.