because it's the only thing left that they can do without it costing them anything. Having brought nuclear weapons to the region with Washington's strong support, the Israelis could not foresee the problem this would cause them, not that Iran plans to launch a nuclear attack on them, since any reasonable person know that's not Iran's intention, the problem being they will no longer be the dominant force in the Middle East, which they so pride themselves on. This to me is really great news, since Israel has been nothing but a brutal tyrant to its neighbors for decades and that's about to change pretty soon.
Jordan foreign minister says to speak with Kerry on Israel-Palestinian conflict (Reuters)
from the article: Former MI chief: Iran has enough material for 4 or 5 nuclear bombs