Ayatollah Ruhollah Khomeini formed the Islamic Revolutionary Guard Corps (IRGC) in 1979 to protect his regime against external and domestic threats. The IRGC has opposed US policies in the Middle East since the IRGC's founding in 1979. The IRGC controls the Iranian nuclear weapon program and their quest for nuclear weapons is a long-term challenge to US interests. Iran's pursuit of nuclear technology and enrichment capabilities also poses a serious challenge to the United States' strategic partners: Israel, Saudi Arabia, Egypt, Turkey, and Pakistan. The Revolutionary Guard has sponsored insurgent groups such as Hezbollah, Muqtada Sadr's Jaysh al-Mahdi, and Hamas because the IRGC has a goal to spread a Shi'i version of totalitarian Islam. This paper is an analysis of the IRGC's nuclear weapon program and the IRGC's sponsorship of militant Islamic groups. This paper also assesses possible US government responses: multilateral sanctions, regional alliances, covert action, and overt military action. The United States must address the impacts of Iran's missile arsenal, the concern for Israel's safety, the integrity of the Persian Gulf shipping lanes within the Strait of Hormuz, and the possibility of Iranian coordination of terrorist attacks around the globe.