JMM is right. If Netanyahu and other Israeli hardliners really thought that an Iranian nuclear bomb was a threat to Israel's existence, they would not be trying to imposing other extraneous conditions on the deal, like recognition of Israel. (At least Yuval Steinitz's demands focus on the nuclear issue, But that's a little different from what his boss has been saying)
Once again, I think what Israeli critics really fear about the Iranian nuclear deal is rapprochement between Iran and the West. A lot has happened since the U.S. broke off relations with Iran in 1979. These days there are a growing number of issues that Iran and the U.S.are effectively on the same side (the fight against ISIS is the obvious example). That prospect, not a nuclear deal, is what really terrifies the Israelis, and for that matter Sunni Arab countries like Saudi Arabia, the other members of the GCC, and Egypt.
Once again, I think what Israeli critics really fear about the Iranian nuclear deal is rapprochement between Iran and the West. A lot has happened since the U.S. broke off relations with Iran in 1979. These days there are a growing number of issues that Iran and the U.S.are effectively on the same side (the fight against ISIS is the obvious example). That prospect, not a nuclear deal, is what really terrifies the Israelis, and for that matter Sunni Arab countries like Saudi Arabia, the other members of the GCC, and Egypt.