The U.S. designation of the Islamic Revolutionary Guard Corps (IRGC) as a Foreign Terrorist Organization (FTO) is the latest manifestation of the U.S. policy of “maximum pressure” on Iran. Tehran has always emphasized reciprocity, responding “in kind” to perceived challenges. It has employed that logic in this case as well, “designating” U.S. Central Command (CENTCOM) “and all its affiliates” as a terrorist organization in response to the U.S. move. Beyond “designating” the U.S. military, however, Tehran may try to respond in ways that more tangibly affect U.S. interests.
As long as Tehran opts to stay in the 2015 nuclear deal, known formally as the Joint Comprehensive Plan of Action (JCPOA), it is constrained in the nuclear arena in responding to U.S. pressure. But it has options in other domains, where it could:
further ramp up the detention and imprisonment of U.S. citizens and dual-nationals (resumed in early 2017);
accelerate the assassination of oppositionists in Europe (resumed in 2015 after a decades-long halt, and accelerated in 2017 and 2018)—which may have the added benefit of hindering perceived U.S. regime change plans;
further ramp up the test and operational use of short- and medium-range missiles (which it more or less halted during the nuclear negotiations and resumed thereafter);
resume the harassment of U.S. naval vessels in the Persian Gulf (largely halted in mid-2017);
disrupt maritime traffic in the Strait of Hormuz (which it has threatened to do if it can no longer export oil—but which it is unlikely to do as long as it is still exporting oil and importing goods through the Strait);
resume disruptive cyber operations against the United States (halted when nuclear negotiations gained traction in 2013, though cyber spying has continued without interruption); and
use its militant proxies in Iraq (or elsewhere) to renew attacks on U.S. personnel, which ceased following the withdrawal of U.S. forces from Iraq in 2011 (Iranian proxies rocketed U.S. diplomatic facilities in Basra in late 2018, causing the United States to close its consulate there).
Iran has already commenced its pushback against the U.S. policy of “maximum pressure,” as indicated by the aforementioned activities conducted since the conclusion of the nuclear deal in 2015. The question is, how will it respond to a move—the designation of the IRGC as an FTO—that is unlikely to have a major impact on an already heavily sanctioned organization and economy? The rather limited impact of this latest U.S. step would seem to argue for a response that is more muted than dramatic. Moreover, several of the response options have but a tenuous link to the IRGC designation, likely ruling them out. Detaining additional U.S. citizens, a series of missile tests, or renewed harassment of U.S. vessels in the Gulf are low-risk options that Iran could pursue in response to this step. But it will tread more cautiously when it comes to renewed lethal attacks against U.S. personnel in the region, because the United States is a powerful and unpredictable adversary with the capacity to cause it great harm. The IRGC FTO designation is unlikely to change that aspect of Tehran's calculus in responding to the U.S. designation.
Yet, there may be individuals in the IRGC who favor hitting back at the United States. Some hardliners understand that President Donald Trump is looking for a reason to pull the United States out of the region and believe that he is all bluff on confronting Iran militarily. They may argue that Tehran should sponsor an attack on U.S. troops along the lines of the Marine Barracks Bombing in Beirut, Lebanon (1983) or Khobar Towers in Saudi Arabia (1996), to give the United States the final shove it needs to leave the region. As Washington applies “maximum pressure,” it should keep this in mind, and constantly tend to and monitor its deterrent posture in the region to influence Tehran's calculus and avert such an eventuality.
Michael Eisenstadt is the Kahn Fellow and director of the Military and Security Studies Program at The Washington Institute.