Secretary of State Mike Pompeo announces the Trump administration's plan to designate Iran's Islamic Revolutionary Guard Corps as a foreign terrorist organization on April 8. (Patrick Semansky/AP)

The Trump administration announced Monday that it would designate Iran’s Islamic Revolutionary Guard Corps (IRGC) as a foreign terrorist organization (FTO), adding another layer of sanctions on Iran. An unprecedented step in U.S. foreign relations, this marks the first time that the U.S. government has listed a state military as a terrorist organization, alongside al-Qaeda, the Islamic State, Red Army Faction and numerous other proscribed organizations. The move makes the IRGC subject to the broadest mechanisms of legal and financial pressure by the United States.

The potential action has already been praised by Iran hawks, who see it as justified and as a necessary step in the effort to build maximum pressure on Iran’s ruling regime. To compel the Islamic Republic to change its behavior both internally and regionally, they reason, the regime should be isolated, marginalized and weakened by all available measures of American soft power.

Such a step will be welcomed by Iran’s adversaries as well, particularly Saudi Arabia, the United Arab Emirates and Israel, which have long lobbied Washington to take a harder line toward Tehran. These states view the IRGC as the spearhead of Iran’s destabilizing support to proxies in Yemen, Gaza, Syria and Lebanon. They further consider the IRGC to be a direct military threat, particularly because of the organization’s leading role in building up Iran’s ballistic missile program.

In many ways, this step is unsurprising. The IRGC has already been targeted by numerous, albeit lesser, U.S. sanctions and designations. The recent history of IRGC-related sanctions goes back to the U.S.-led occupation of Iraq when IRGC-sponsored Shiite militant groups actively opposed U.S. forces and were a leading source of U.S. causalities. In 2007, Sens. Jon Kyl (R-Ariz.) and Joseph Lieberman (I-Conn.) introduced an amendment to House Resolution 1585 that would have provided legal backing for potential military action against Iran. They called for the IRGC to be designated an FTO and placed on the list of “Specially Designated Global Terrorists.” Their amendment met resistance, particularly from Sen. Jim Webb (D-Va.), who worried, in part, that listing the IRGC could be taken as congressional support for a war with Iran. A compromise was made, and instead of designating the military unit in its entirety, only its special forces wing, the Quds Force, was listed.

Since then, both the Obama and Trump administrations have placed numerous sanctions on IRGC entities and officials. Most have targeted the IRGC’s vast commercial empire, including dozens of front companies, and other activities connected to Iran’s nuclear and ballistic missile programs, human rights abuses and foreign operations. The Quds Force has continued to receive the most attention and has incurred sanctions for its involvement in Syria, Afghanistan, Lebanon and Yemen. Banks, airlines, shipping firms and other commercial entities, along with individuals associated with them, have been designated for their links to the IRGC and the Quds Force. Similarly, the IRGC’s foreign clients, such as Lebanese Hezbollah and various Iraqi militias, have also been listed.

The vast network of designations related to the IRGC is the foundation of the overall sanctions regime against the Islamic Republic. Because the IRGC is a state entity, and because it is already heavily intertwined with the state’s economy and foreign relations, sanctions against the IRGC have made it very difficult for countries to do business with Iran. Even though the 2015 nuclear agreement with Iran, the Joint Comprehensive Plan of Action (JCPOA), resulted in the United States and United Nations ending major financial sanctions on the country, the United States’ parallel sanctions on the IRGC have remained in force. The Trump administration has continued to build on those sanctions and, after withdrawing from the JCPOA in 2017, introduced new unilateral sanctions aimed at undermining Iran’s economy.

This designation may not substantially add to the pressures already placed on Iran, but it is a drastic and escalatory move. Initially, it could complicate U.S. relations with Iraq, where the IRGC currently operates openly alongside its Iraqi partners. The United States has already tried to encourage the Iraqi government to end its trade with Iran to bring Baghdad in-line with U.S. financial sanctions, but hasn’t been able to force the matter because of Iraq’s economic dependence on Iran. If the United States tries to compel Iraq to break relations with the IRGC, it is likely to run into stiff resistance. The IRGC heavily supports the Popular Mobilization Forces, an official Iraqi military organization, and has close ties with countless powerful Iraqi politicians and organizations.

Iranian officials have already lambasted the threat of such a designation and warned that Iran would respond in kind by designating the U.S. military. That might sound silly, but it could also cause real problems. Should Iran officially consider U.S. forces to be terrorists, then any personnel connected to the U.S. military could be subject to attacks by Iranian proxies or Iranian agents. This would make U.S. operations in Iraq much more dangerous. The potential for escalation between the United States and Iran would increase, with any attacks on U.S. troops by Iranian proxies or tense encounters at sea between the United States and IRGC navies carrying the greater potential for military escalation.

More broadly, designating the IRGC an FTO will be difficult for any future administration to walk back from. Any administration that seeks to engage Iran diplomatically will have a difficult time getting around the IRGC’s central position in the Islamic Republic. In effect, designating the IRGC is designating the Islamic Republic by proxy. It is difficult to foresee any future administration pushing for a softer stance against the IRGC; the supporters of such a move are likely to be few and the opponents many. The already distant prospect of improved U.S.-Iran relations has become even more unlikely.

Afshon Ostovar is an assistant professor of National Security Affairs at the Naval Postgraduate School in Monterey, Calif. All views and opinions expressed are his own.