A sad reality - the alternative.
Israel will not be happy until it can provoke a war with Iran which the US will fund and fight. Unfortunately, treaty obligations to Israel guarantee the US can and will be sucked into such a conflagration. It would be a much larger affair than the war in Iraq.
Whatever that can be done to avoid that is worth it, including letting Iran have the bomb. After all, Israel is the rogue nation, attacking whomever in the neighborhood she feels like with impunity, because of the hold she has on the US which prevents retaliation.