It seems that not every Arab state and leader in the Middle East is excited about the prospect of a nuclear Iran. An it's not because they suddenly love Israel. It is because the solidarity that they share when ganging up against Israel only goes so far, and it is not inconceivable that Iran might want to use its new weapon against other Arab states as well.
The anti-Israel statements of the Iranian president, Mahmoud Ahmadinejad, coupled with Iran's support for Hezbollah and Hamas, might lead you to think that the Arab states would welcome Iran's nuclear program. After all, the call to wipe the Zionist regime from the map is a longstanding cliché of Arab nationalist rhetoric. But the interests of Shiite non-Arab Iran do not always coincide with those of Arab leaders. A nuclear Iran means, at the very least, a realignment of power dynamics in the Persian Gulf. It could potentially mean much more: a historic shift in the position of the long-subordinated Shiite minority relative to the power and prestige of the Sunni majority, which traditionally dominated the Muslim world. Many Arab Sunnis fear that the moment is ripe for a Shiite rise. Iraq's Shiite majority has been asserting the right to govern, and the lesson has not been lost on the Shiite majority in Bahrain and the large minorities in Lebanon and Saudi Arabia. King Abdullah of Jordan has warned of a "Shiite crescent" of power stretching from Iran to Lebanon via Iraq and (by proxy) Syria.
But geopolitics is not the only reason Sunni Arab leaders are rattled by the prospect of a nuclear Iran. They also seem to be worried that the Iranians might actually use nuclear weapons if they get them. A nuclear attack on Israel would engulf the whole region. But that is not the only danger: Sunnis in Saudi Arabia and elsewhere fear that the Iranians might just use a nuclear bomb against them. Even as Iran's defiance of the United States and Israel wins support among some Sunnis, extremist Sunnis have been engaging in the act of takfir, condemning all Shiites as infidels. On the ground in Iraq, Sunni takfiris are putting this theory into practice, aiming at Shiite civilians and killing them indiscriminately. Shiite militias have been responding in kind, and massacres of Sunni civilians are no longer isolated events.



