1979–1988: rupture and the Iran-Iraq war
The 1979 revolution overturned the US-allied Shah and established the Islamic Republic. The hostage crisis at the US embassy in Tehran (November 1979 – January 1981) ended formal diplomatic relations, which have not been restored. The 1980–1988 Iran-Iraq war was the formative experience for the Iranian state's security thinking, including the institutionalisation of the IRGC.
1990s–2000s: sanctions architecture
Successive US administrations built the sanctions architecture against Iran in stages: ILSA (1996), executive orders restricting trade and finance, and post-2006 UN sanctions linked to the nuclear programme. The Bush administration named Iran in the "axis of evil" in 2002; the post-2003 occupation of Iraq created a new theatre where US and Iran-aligned forces operated in proximity.
2010s: JCPOA, withdrawal, and maximum pressure
The 2015 Joint Comprehensive Plan of Action limited Iranian enrichment in exchange for sanctions relief. The 2018 US withdrawal under the Trump administration restored and expanded sanctions. The 2020 killing of IRGC-Quds Force commander Qassem Soleimani in Iraq marked the highest direct US-Iran kinetic escalation in decades.
2020s: regional proliferation
The post-October-2023 conflict environment expanded the canvas: Houthi maritime operations in the Red Sea, Hezbollah and Israeli exchanges across the Lebanon-Israel border, Iran-aligned militia activity in Iraq and Syria, and direct Iran-Israel exchanges. The Iranian nuclear programme's enrichment level has been the throughline.