Nations around the world are uncertain and anxious about Iran's intentions in the Middle East and the wider global arena. Its current president, Mahmoud Ahmadinejad, has made no secret of his opposition to Western society, particularly Israel, and his desire to acquire nuclear weapons. However, as Anthony H. Cordesman and Martin Kleiber point out, Ahmadinejad does not necessarily speak for the Iranian clerical regime, who operate in a cloud of secrecy and also directly control Iran's military. Given the ambiguous nature of Iran's global objectives, this new study focuses on the tangible aspects of Iran's military forces and takes an objective look at the realistic threats that Iran poses to the region and the world. The authors systematically assess each aspect of Iranian military forces from their conventional armies to their asymmetric threat via proxy wars in the region. Much attention in national security debates is paid to Iran's intentions without first understanding its capabilities. Lacking such a fundamental understanding, much of this speculation tends to be wasted and irrelevant to what could actually happen in the event of a conflict. Cordesman and Kleiber's study provides, in meticulous detail, a basis for understanding the realistic threat that Iran poses to the Northern Gulf.