Despite dangerously high tensions between the United States and Iran, which are rooted in the fundamentally different foreign policy objectives of each country, the risks of open hostilities between the two sides are kept in check by the realization of the catastrophic consequences involved. The conflict between the two sides is one of fundamental foreign policy visions and principles that often — especially since the start of President Bush’s second term — verge on the irreconcilable. The stakes of this dangerous rivalry are high, and the range of possible scenarios for moving beyond it is perilously limited. At the same time, however, both sides appear to be keenly aware of the catastrophic consequences of open hostilities between them, and thus seek to undermine the other’s interests without stepping beyond certain ill-defined red lines. High-level US-Iranian tensions are likely to continue for some time, therefore, without, however, spilling into open warfare.