The US and Israel would make a terrible mistake by trying to bomb the Iranian development sites in the "humane" manner. Such a plan of "underbombing" Iran was recently leaked by this newspaper, the plan that included several conventional weapons and one "tactical" nuke used against the nuclear plant only. Such "underbombing" would still cause "universal condemnation" but no real damage to the undeground facilities. The Europeans and the arabs would formally "condemn" Israel no matter what. But all would be much happier if Israel (or US) does a complete job by wiping out most of the sites with the multiple strategic nuclear weapons. Only such megatons-rated weapons make craters large enough to penetrate the protective Earth layers.
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from the article: Ahmadinejad: Israel and the U.S. would not dare attack Iran