This parallel to India and Pakistan does not work as an argument. There, both countries could be (and have been) going at eachother without nuclear deterrence, so it has probably increased the security of both countries.
In the case of Israel and Iran, only one side would realistically try to wipe out the other side in a conventional war, were there no nukes. If Iran leaves Israel alone (as it will, due to Israel's nuke capability), it has no risk of being attacked by Israel whatsoever. In fact, if Iran behaves itself and remains non-agressive, it does not need any nuclear deterrent at all. That is not the case with Israel, which is why they need their nukes. But all other countries in the Middle East don't - as long as they're non-agressive vis-a-vis Israel. Which may be the problem...
In the case of Israel and Iran, only one side would realistically try to wipe out the other side in a conventional war, were there no nukes. If Iran leaves Israel alone (as it will, due to Israel's nuke capability), it has no risk of being attacked by Israel whatsoever. In fact, if Iran behaves itself and remains non-agressive, it does not need any nuclear deterrent at all. That is not the case with Israel, which is why they need their nukes. But all other countries in the Middle East don't - as long as they're non-agressive vis-a-vis Israel. Which may be the problem...
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