This report analyzes four key aspects of US and Iranian strategic competition--sanctions, energy, arms control, and regime change. Its primary focus is on the ways in which the sanctions applied to Iran have changed US and Iranian competition since the fall of 2011. This escalation has been spurred by the creation of a series of far stronger US unilateral sanctions and the European Union's imposition of equally strong sanctions, both of which affect Iran's ability to export, its financial system, and its overall economy.