The likely responses of Saudi Arabia, Egypt and Turkey to Iranian acquisition of a nuclear weapon were considered in a new staff report (pdf) from the Senate Foreign Relations Committee.
“How are these three countries responding today to the Iranian nuclear program? How would Riyadh, Cairo, and Ankara respond if Tehran were to cross the nuclear threshold and acquire nuclear weapons? Would they pursue nuclear weapons of their own? What factors would influence their decisions? What can the U.S. do now and over the coming years to discourage these countries from pursuing a nuclear weapon of their own?”
“Based on 5 months of research and interviews with hundreds of officials and scholars in the United States and seven Middle Eastern countries, this report attempts to answer these questions.”
See “Chain Reaction: Avoiding a Nuclear Arms Race in the Middle East,” Senate Foreign Relations Committee print, February 2008.