As the world's leading state sponsor of terrorism, Tehran relies on the IRGC to destabilize the entire Middle East. Although the IRGC and its paramilitary arm, the Quds Force, have been subject to sanctions since 2007 even without their FTO designation, delisting them would send a fatal signal of weakness not only to the regime in Tehran, but also to the autocrats in China and Russia - with unforeseeable consequences for security and peace.
The FTO designation has little to no practical value and is mere tokenism. When Washington fears - as it has for years - that Iran is "just weeks" away from being able to build a nuclear weapon, reviving the nuclear agreement should be the highest US national security interest - not targeting the IRGC.