The MISSILES Act aims to close a legal gap created when key United Nations restrictions on Iran's missile and drone technology, set out in Annex B of UN Security Council Resolution 2231, expired in October 2023. The bill directs the State Department to pursue a diplomatic strategy to renew these international restrictions and requires several detailed reports to Congress over the next few years covering Iran's missile and drone supply chains, sanctioned Iranian airlines, and the broader impact of U.S. sanctions on Iran's economy, military capabilities, and civilian population. It also establishes new U.S. sanctions, including asset freezes and visa bans, targeting foreign individuals, companies, or governments that knowingly help Iran or Iran-aligned groups like Hezbollah and the Houthis acquire, develop, or transfer missile and drone technology, with the President required to issue implementing regulations within 120 days. Additionally, it mandates that any Iranian person who uses drones to attack U.S. citizens be identified and designated as a foreign terrorist organization, a designation that cannot be reversed for at least four years. The sanctions and terrorist designations include national-security waivers the President can invoke, and the sanctions section terminates only if Iran verifiably ends its support for terrorism and dismantles its weapons of mass destruction and missile programs.