Relations between Iran and the United States began in the mid-19th century, when Iran was known to the Western world as Qajar Persia. While Persia was the object of British and Russian colonial interests during the Great Game, the US gained the trust of its leaders, with Arthur Millspaugh and Morgan Shuster appointed treasurers-general by the Shahs. During World War II, Iran was invaded by the United Kingdom and the Soviet Union, both U.S. allies. Relations remained positive until the Mohammad Mosaddegh government was overthrown by the 1953 Iranian coup d'état, organized by the Central Intelligence Agency, and assisted by MI6. This was followed by an alliance between Shah Mohammad Reza Pahlavi's regime and the US government. From being close allies during the Cold War,Jenkins, Philip (2006). Decade of Nightmares: The End of the Sixties and the Making of Eighties America: The End of the Sixties and the Making of Eighties America p. 153. Oxford University Press, US. Little, Douglas (2009). American Orientalism: The United States and the Middle East since 1945. p. 145. Univ of North Carolina Press. Murray, Donette (2009). US Foreign Policy and Iran: American–Iranian Relations Since the Islamic Revolution p. 8. Routledge. Iran-US relations flipped after the 1979 Iranian Revolution, when Ayatollah Ruhollah Khomeini took power.
The two nations have had no formal diplomatic relations since 1980: Pakistan and Switzerland serving as protecting powers for Iran and the US respectively. Communication goes through the Pakistani Embassy in Washington and the Swiss Embassy in Tehran.Embassy of Switzerland in Iran – Foreign Interests Section , Swiss Federal Department of Foreign Affairs (page visited on April 4, 2015). Since 1995, the United States has had an embargo on trade with Iran. Relations improved when the two countries had overlapping goals, such as joining forces in the war against the Islamic State.The Middle East and North Africa 2003, eur, 363, 2002 In 2015, the Joint Comprehensive Plan of Action to limit Iran's nuclear program was signed; most sanctions against Iran were lifted the next year.Akbar E. Torbat, Politics of Oil and Nuclear Technology in Iran, Palgrave MacMillan, 2020, The first Trump administration withdrew from the deal and re-imposed sanctions in 2018; in August, former Supreme leader Ali Khamenei banned direct talks with the United States. In the years that followed Iran reduced its deal commitments and exceeded pre-JCPOA enrichment levels. The Biden administration increased sanctions; so did the second Trump administration.
On February 28, 2026, Israel and the United States launched a joint attack on various sites in Iran, beginning a war between the three countries. The operation included the assassination of Ali Khamenei, Iran's supreme leader. After three months of war, the US and Iran announced on June 14, 2026, that they had agreed to halt hostilities. Mediated by Pakistan and Qatar, the memorandum of understanding presented a 60-day extension of the existing ceasefire to lay the groundwork for a final settlement.
History
Early relations American newspapers in the 1720s were uniformly pro-Iranian, especially during the revolt of Afghan emir Mahmud Hotak () against the Safavid dynasty.
Political relations between Qajar Persia and the United States began when the Shah of Iran, Nassereddin Shah Qajar, officially dispatched Iran's first ambassador, Mirza Abolhasan, to Washington, D.C. in 1856.The Middle East and the United States: A Historical and Political Reassessment, David W. Lesch, 2003, , p. 52 In 1883, Samuel G. W. Benjamin was appointed by the United States as the first official diplomatic envoy to Iran; however, ambassadorial relations were not established until 1944.
The U.S. had little interest in Persian affairs, while the U.S. as a trustworthy outsider did not suffer. The Persians again sought the U.S. for help in straightening out its finances after World War I. This mission was opposed by powerful vested interests and eventually was withdrawn with its task incomplete.
During the Persian Constitutional Revolution in 1909, American Howard Baskerville died in Tabriz while fighting with a militia in a battle against royalist forces. After the Iranian parliament appointed United States financier Morgan Shuster as Treasurer General of Iran in 1911, an American was killed in Tehran by gunmen thought to be affiliated with Russian or British interests. Shuster became even more active in supporting the Constitutional Revolution of Iran financially.Ibid. p. 83
Arthur Millspaugh, an American economic adviser, was sent to Persia in 1923 as a private citizen to help reform its inefficient administration. His presence was seen by Persians as a means to attract foreign investment and counterbalance European influence. The mission ended in 1928 after Millspaugh fell out of favor with the shah.
Until World War II, relations between Iran and the United States remained cordial. As a result, many Iranians sympathetic to the Persian Constitutional Revolution came to view the U.S. as a "third force" in their struggle to expel British and Russian dominance in Persian affairs. American industrial and business leaders were supportive of Iran's drive to modernize its economy and to expel British and Russian influence from the country.
Reza Khan, a military officer in Persia's Cossack Brigade, came to power after leading a British-backed coup in 1921 that overthrew the Qajar dynasty.Zirinsky M.P. Imperial Power and dictatorship: Britain and the rise of Reza Shah 1921–1926. International Journal of Middle East Studies. 24, 1992. p. 646*Foreign Office 371 16077 E2844 dated June 8, 1932. The Memoirs of Anthony Eden are also explicit about Britain's role in putting Reza Khan in power. Ansari, Ali M. Modern Iran since 1921. Longman. 2003 pp. 26–31 He later declared himself shah (king) and took the name Reza Pahlavi. He launched modernization efforts, building a national railway and introducing secular education, while also censoring the press, suppressing unions and parties, and later banning the hijab in favor of Western dress. In 1936, Iran withdrew its ambassador in Washington for nearly one year after the publication of an article criticizing Reza Shah in The New York Daily Herald.
After a dispute over German influence during World War II, Reza Shah was forced to abdicate in 1941 and was succeeded by his son, Mohammad Reza Pahlavi. During the rest of World War II, Iran became a major conduit for British and American aid to the Soviet Union and an avenue through which over 120,000 Polish refugees and Polish Armed Forces fled the Axis advance. At the 1943 Tehran Conference, the Allied "Big Three"—Joseph Stalin, Franklin D. Roosevelt, and Winston Churchill—issued the Tehran Declaration to guarantee the post-war independence and boundaries of Iran. In 1949, the Constituent Assembly of Iran gave the shah the power to dissolve the parliament.
1953 Iranian coup d'état Before the coup
Until the outbreak of World War II, the United States had no active policy toward Iran.Stephen Kinzer All the Shah's Men: An American Coup and the Roots of Middle East Terror, John Wiley and Sons, 2003, p. 86 When the Cold War began, the United States was alarmed by the attempt by the Soviet Union to set up separatist states in Iranian Azerbaijan and Kurdistan, as well as its demand for military rights to the Dardanelles in 1946. This fear was enhanced by the loss of China to communism, the uncovering of Soviet spy rings, and the start of the Korean War.Byrne writing in Mohammad Mosaddeq and the 1953 Coup in Iran, Edited by Mark J. Gasiorowski and Malcolm Byrne, Syracuse University Press, 2004, pp. 201, 204–06, 212, 219.
Prime minister Mossadeq In 1951, Iran nationalised its oil industry, effectively seizing the assets of the Anglo-Iranian Oil Company (AIOC). On April 28, 1951, Mohammad Mosaddegh was elected as Prime Minister by the Parliament of Iran.
The British planned to retaliate by attacking Iran, but U.S. President Harry S. Truman pressed Britain to moderate its position in the negotiations and to not invade Iran. American policies fostered a sense in Iran that the United States supported Mossadeq, along with optimism that the oil dispute would soon be resolved through "a series of innovative proposals" that would provide Iran with "significant amounts of economic aid." Mossadeq visited Washington, and the American government made "frequent statements expressing support for him."Gasiorowski writing in Mohammad Mosaddeq and the 1953 Coup in Iran, Edited by Mark J. Gasiorowski and Malcolm Byrne, Syracuse University Press, 2004, p. 273
At the same time, the United States honored the British embargo and, without Truman's knowledge, the Central Intelligence Agency station in Tehran had been "carrying out covert activities" against Mosaddeq and the National Front "at least since the summer of 1952".Gasiorowski writing in Mohammad Mosaddeq and the 1953 Coup in Iran, Edited by Mark J. Gasiorowski and Malcolm Byrne, Syracuse University Press, 2004, p. 243
The coup d'état
In 1953, the U.S. and Britain orchestrated a coup to overthrow Iran's prime minister Mohammad Mosaddeq, fearing communist influence and economic instability after Iran nationalized its oil industry. The coup, led by the CIA and MI6, initially failed but succeeded on a second attempt. It reinstalled Shah Mohammad Reza Pahlavi, who then received substantial U.S. financial and military support. The U.S. helped establish SAVAK, the Shah's brutal secret police, to maintain his rule. Many liberal Iranians believe that the coup and the subsequent U.S. support for the shah enabled the Shah's arbitrary rule, contributing to the "deeply anti-American character" of the 1979 revolution later.Gasiorowski, Mohammad Mosaddeq and the 1953 Coup in Iran, Edited by Mark J. Gasiorowski and Malcolm Byrne, Syracuse University Press, 2004, p. 261
After the coup, the United States played a central role in reorganizing Iran's oil sector. Under U.S. pressure, BP joined a consortium of Western companies to resume Iranian oil exports.Marius Vassiliou, Historical Dictionary of the Petroleum Industry : Volume 3]]. p. 269.Lauterpacht, E. International Law Reports. p. 375. The consortium operated on behalf of the state-owned National Iranian Oil Company (NIOC), which retained formal ownership of Iran's oil and infrastructure. While Iran received 50% of the profits, U.S. companies collectively secured 40% of the remaining share.Strategies, Markets and Governance: Exploring Commercial and Regulatory Agendas. p. 235. However, the consortium maintained operational control, barred Iranian oversight of its financial records, and excluded Iranians from its board.Kinzer, All the Shah's Men, (2003), pp. 195–6. The agreement was part of a wider transition from British to American dominance in the region and worldwide.
While initially seen as a Cold War success, the coup later became a source of deep resentment, with critics calling it a blow to democracy and a lasting stain on U.S.-Iran relations.
U.S.–Shah alliance
Nuclear cooperation In 1953, U.S. President Eisenhower launched Iran's nuclear program as part of Atoms for Peace program. In 1967, the U.S. helped Iran create its nuclear program by providing the Tehran Research Reactor, the nation's first nuclear reactor, as well as 5.58 kg of enriched uranium.Mustafa Kibaroglu, "Good for the shah, banned for the mullahs: The west and Iran's quest for nuclear power." Middle East Journal 60.2 (2006): 207-232 online . Iran is one of the 51 original signatories of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) on July 1, 1968, and its Parliament ratified the treaty in February 1970. The participation of the U.S. and Western European governments continued until the 1979 Iranian Revolution.
Strategic alliance and geopolitical importance