Book excerpt: Iran's possible acquisition of nuclear weapons along with more assertive Iranian foreign policies poses new security challenges for Turkey in the Middle East. A nuclear-weapons-capable Iran with its important strategic position would pose a great danger to peace and stability in the Middle East. An Iran with the capability of mass destruction would fundamentally alter the balance of power and this situation is not acceptable for Turkey's security. Turkey expects Iran to adopt a more moderate and cooperative approach in the diplomatic negotiations over its nuclear program. For this reason, Turkey has adopted a soft diplomacy approach against Iran's nuclear program. But this ambiguous diplomacy against nuclear weapons does not provide a clear definition of Turkey's goals or policies with sets of political actions to deter the development of weapons of mass destruction by Iran in the region. What policy should Turkey adopt against the Iran nuclear crisis? This thesis will attempt to answer this question in terms of shaping Turkey's state policy against a nuclear Iran, evaluating the defense options of Turkey, and giving policy recommendations for the near-future situation in the region.