Israel should have nuclear weapons because her very existance is threatened. The threats are real, as demonstrated by the aggressive nature of her neighbours and the history of the Jewish people. The only threat that Iran faces is from its own government and the religious establishment in that country. Its not a double standard to leave weapons with those who are threatened and who have for decades demonstrated responsible non-use of those weapons, whilst at the same time keeping weapons out of the hands of mad-men (as in much of the Islamic world). It would not be in Israel's interest for her to be without very serious weaponry that could help equalize the battlefield. Without those weapons the sheer numbers, size and wealth of the insane, belligerent and delusional countries and peoples that surround her, would be a recipe for yet another slaughter house experience.
Kerry meets Egyptian officials in bid to assuage concerns over Iran deal (AP)
from the article: Obama 'strongly' opposes singling out of Israel at nuclear conference