Many western politicians and commentators have described Iran's national security policies in the years after the Islamic Revolution as antagonistic, “breaking the rules of the game" and threatening to other countries. While most Iranian scholars have argued that Iran should not be viewed as a threat to the Middle East and the international society at large. In fact, their counter-argument is that the post-1979 Iran has played a “pacifying” role in its unstable and conflict-prone environment. Important dimensions of Iran’s defense policy will be examined in order to find answers to the following questions: What are the main challenges and opportunities for Iran’s ambition to improve its relative power position in the region, considering the perceptions of the great powers and key regional states of the “Iran threat”? Is Iran’s foreign and security policies expansionist or defensive? Should its defense policy be viewed as a threat to regional security?