Read this entire sobering piece from Daniel Pipe's Weblog:
The Unthinkable Consequences of an Iran-Israel Nuclear Exchange
November 21, 2007
He expects, writes Martin Walker of United Press International,
some 16 million to 28 million Iranians dead within 21 days, and between 200,000 and 800,000 Israelis dead within the same time frame. The total of deaths beyond 21 days could rise very much higher, depending on civil defense and public health facilities, where Israel has a major advantage.
It is theoretically possible that the Israeli state, economy and organized society might just survive such an almost-mortal blow. Iran would not survive as an organized society. "Iranian recovery is not possible in the normal sense of the term," Cordesman notes. The difference in the death tolls is largely because Israel is believed to have more nuclear weapons of very much higher yield (some of 1 megaton), and Israel is deploying the Arrow advanced anti-missile system in addition to its Patriot batteries. Fewer Iranian weapons would get through.
Further, Cordesman expects that Israel would need to keep a "reserve strike capability to ensure no other power can capitalize on Iranian strike" and might target "key Arab neighbors"— Syria, Egypt, and the Persian Gulf states.