If Iran acquires nuclear weapons, Israel faces five risks. First, a direct and existential threat will be created, as a regime that questions the existence of Israel will have acquired nuclear weapons. Second, an Iranian nuclear umbrella will be established in the Middle East. Under such circumstances, any conflict in the Middle East, whether Israel is involved or not, will be affected by Iran’s ‘‘nuclear signals.’’ For instance, if there is another military confrontation between Israel and Hezbollah and Iran elevates the readiness of the nuclear division, while declaring that far-reaching Iranian retaliation should not be excluded, Israel might be deterred and stop the military operation in Lebanon. Third, an arms race in the Middle East will erupt as other countries such as Egypt, Saudi Arabia, and Turkey will not be able to avoid the need to obtain nuclear weapons. Consequently, the nonproliferation regime will collapse. Fourth, internal stability would erode in Arab countries where Shi‘ites are struggling for their political status. The largest danger is in Saudi Arabia, where the Shi‘ite minority (20 percent), living in an area replete with oil, could demand its relative share of national wealth or perhaps even more, such as autonomy. Fifth, a nuclear Iran would serve Mahmoud Ahmadinejad’s legacy and be seen as a victory for Islam, which could potentially motivate other Muslim states or Muslim communities in non-Muslim states to increase demands.