this is a threat against Iran (and Iraq, Syria, and Lebanon).
we need 2,000 Shahab-3/Ghadr/Rezvan class MRBMs to deplete Israel's ABM interceptors (over a sustained period). thankfully this already exists as of 2012 even. A few hundred Fattah-1/2 missiles to destroy the Green Pine / TPY-2 radars. Thousands of Khorramshahr missiles to pulverise Tel Aviv on a daily basis. But ultimately only nuclear weapons will deter Israel. If the US refuses to attack Iran on behalf of Israel, it is easy to imagine that Israel will quickly resort to new levels of barbarism and terrorism against Iranian civilians to increase pressure on the Iranian leadership.
Israel routinely kills 100 Palestinian civilians to target 1 Hamas fighter. They would likely happily slaughter 1,000 Iranian civilians to target 1 IRGC commander.