This is a point Geoffrey Kemp and I dwell on extensively in our forthcoming book War with Iran: Political, Military, and Economic Consequences. Robb, Ross and Makovsky are right to point out that there are substantial costs associated with a nuclear-armed Iran. Increasing tension in the region could certainly add to the security premium on Gulf oil. Fears of supply disruption increase demand for futures contracts as consumers attempt to ensure they won’t run out of oil. Further, the United States and its regional allies would have to deter and balance a more powerful Iran. This would have costs of its own: troops deployed in the region are financially and politically expensive; weapons given to Gulf allies would raise the stakes of a conflict (and of instability); resources sent to the Middle East cannot be used elsewhere, such as for America’s strategic shift to East Asia.