Maybe it's all a clever bluff by Israel,and they haven't got any bombs after all. If they had said they did have bonbs people would go being sceptical about it, and saying "prove it" - as it is they've got the same deterrent effect, but maybe saved all the hassle of making the things. All they needed to do was set up Moredecai Vanunu as a whistleblower and bang him up for ever, and everyone takes it as read that they are armed to the teeth.

I don't suppose it would work if Iran tried the same ploy, and instead of saying they don't have any bombs and have no intention of developing them, they just went in for saying "Wouldn't you like to know?" instead...