The United States and Iran have been adversaries since the 1979 Islamic Revolution and the subsequent US embassy hostage crisis in Tehran. This long-standing enmity has seen numerous escalations and confrontations.
In November 1979, student activists seized 52 hostages at the US embassy, holding them for 444 days. Diplomatic relations were severed in April 1980.
Accusations of state-sponsored terrorism led to a complete US trade and investment ban in 1995. In 2002, Iran was labeled part of an "axis of evil." By April 2019, the US designated Iran's Islamic Revolutionary Guard Corps a "terrorist organization."
Fears surrounding Iran's nuclear program surfaced in the early 2000s. Despite denials, a 2011 IAEA report suggested activities relevant to nuclear weapon development. A landmark nuclear deal was reached in 2015, offering sanctions relief for nuclear assurances. However, the US withdrew in 2018, reimposing sanctions.
In January 2020, the US killed top Iranian general Qasem Soleimani, alleging an imminent attack plot. Iran retaliated with missile strikes on US bases in Iraq.
Recent years have seen further direct confrontations. In June 2025, the US reportedly struck three major Iranian nuclear sites during a conflict with Israel. This was followed by a US military buildup in the Gulf in late 2025 and early 2026 amid protests in Iran. Indirect talks under Omani mediation aimed to avert further escalation, but failed to yield an agreement on Iran's nuclear program, ballistic missiles, and regional support for armed groups, leading to announcements of "major combat operations" by February 2026.