The U.S. and Iran have a complicated history dating back decades.
From the U.S. involvement in the shah’s 1953 coup of Prime Minister Mohammed Mosaddegh, to the Iran hostage crisis in 1979, to the U.S. killing of one of Iran’s top generals in January 2020, the U.S. and Iran’s conservative religious and political leaders have often found themselves in stark opposition to one another about their visions for both Iran’s own future and larger interests in the Middle East.
Throughout the years, there have been periods of decreased tensions, but there have also been times where the two countries have found themselves on the brink of war.
Here’s a look back at U.S.-Iran relations.
1921- Reza Khan names himself shah of Persia
Reza Khan, a military officer in Persia’s Cossack Brigade, names himself shah of Persia after staging a coup, backed by the British, against the government of the Qajar Dynasty. He begins to implement a series of reforms aimed at modernizing the country, which include building a national railroad system and implementing a secular education system. At the same time, he censors the press, suppresses trade unions and bans political parties. Later in his rule, he bans the hijab and encourages western dress.
1925- Ahmad Shah is deposed
Already living in exile, Ahmad Shah, the Qajar dynasty’s final ruler, is deposed, and an assembly votes in Reza Khan (who had adopted the last name Pahlavi) as the new shah.
1935 – Persia is officially renamed Iran
Reza Khan asks other nations to call Persia “Iran” in formal diplomatic correspondence. Also, by the mid-’30s, Reza Khan’s dictatorial approach begins to cause dissent.
1941 – Reza Khan is forced out
Although Reza Khan declares Iran a neutral power during World War II, Iran’s British-controlled oil interests are largely maintained by German engineers and technicians, and Khan refuses to expel German citizens despite a request by Britain. In September 1941, following British and Soviet occupation of western Iran, Reza Shah is forced out of power. His son, Mohammad Reza Shah Pahlavi, succeeds him on the throne.
1949 – The shah’s powers are expanded
Shah Mohammad Reza Pahlavi survives an assassination attempt. Afterward, he calls for the convening of a Constituent Assembly. The group amends the nation’s constitution to give the shah the power to dissolve the parliament.
1951 – Nationalizing the oil industry
Lawmaker Mohammed Mosaddegh, who has gained considerable political power, pushes through a measure that nationalizes the British-owned oil industry in Iran. The same year, the nation’s legislative body overwhelmingly nominates Mossadeq as prime minister, forcing the shah to appoint him to the post.
1953- Mosaddegh overthrown
The power struggle between Mosaddegh and the shah comes to a head when the shah attempts to dismiss Mosaddegh from his position–a move urged by the U.S. Central Intelligence Agency. Protesters take to the streets, forcing the shah to flee the country. But the shah returns to Iran when Gen. Fazlollah Zahedi — with backing from the CIA — overthrows Mosaddegh in an August coup d’etat.
1957 – The creation of Iran’s intelligence organization
U.S. and Israeli intelligence officers work with Iran to set up SAVAK, an Iranian intelligence organization. The organization is later blamed for the torture and execution of thousands of political prisoners and violent suppression of dissent, according to Amnesty International.
1963 – The White Revolution
The shah implements the “White Revolution,” an aggressive campaign of social and economic Westernization that included redistribution of land, increased rights for women and attempts to improve literacy and health in rural areas. The changes are met with opposition from the clerical rules and landlords. Popular nationalist Ayatollah Khomeini is arrested in one of many crackdowns on the shah’s opponents.
September 8, 1978 – Black Friday
A day earlier, the shah had imposes martial law in an attempt to quell ongoing protests against his authoritarian rule. On September 8, thousands gather in Jaleh Square in Tehran, and security forces fire on the protesters. The death toll is unknown. Estimates range from several dozens to hundreds killed.
January 16, 1979 – The shah flees
Protests continue and the shah, who was seen by many as a puppet of the U.S. and the UK, is forced to flee Iran amid the intensifying unrest. He travels to a number of countries before entering the U.S. to receive cancer treatment.
February 1, 1979 – Ayatollah Khomeini returns from exile
Islamic nationalist Ayatollah Khomeini returns from France, where he was exiled for more than 14 years because of his opposition to the shah’s regime. He encourages the brewing revolution.
April 1, 1979 – Iran becomes a theocratic republic
Under Ayatollah Khomeini’s guidance, Iran declares itself a theocratic republic guided by Islamic principles, and a referendum is held to name it the Islamic Republic of Iran.
May 5, 1979 – The Revolutionary Guard Corps is formed
Ayatollah Khomeini issues a decree calling for the formation of a force that would apprehend people involved in counterrevolutionary activities, defend Iran against foreign forces and support revolutionary movements around the world. In the 1980s, one of the now-eight branches of the IRCG– the Quds Force– is created. The group of elite military forces specializes in foreign operations.
November 4, 1979 – Storming of the embassy
Islamic students who were followers of Ayatollah Khomeini storm the U.S. Embassy in Tehran, taking hostage 52 American employees and demand that the shah return from receiving medical treatment in the United States to face trial in Iran. The hostage situation ignites a crisis between the United States and Iran.
April 1980 – The hostage crisis
Iran and the United States sever diplomatic ties over the hostage crisis.
July 1980 – The shah dies
After traveling from the U.S. to Panama and then to Egypt, the shah dies in exile.
September 1980 – The Iran-Iraq War
Iraq invades Iran after years of disagreements over territory, notably oil-rich border regions and the Shatt al-Arab waterway.
1981 – U.S. hostages are released
Following negotiations mediated by Algeria, the U.S. hostages were released after 444 days of captivity, just minutes after Ronald Reagan is sworn in as president.
1985 – Hezbollah is formed
Hezbollah, a Lebanon-based political party and militant group, issues its founding manifesto. The group, which opposes Israel and Western involvement in the Middle East, receives substantial financial support and training from Iran and its Islamic Revolutionary Guard Corps. It is largely seen as a proxy for Iran, and the U.S. has designated it a terrorist organization.
1985 – 1987 – Iran-Contra
The United States covertly seeks to sell arms to Iran. The money from the sales was supposed to be in exchange for seven American hostages being held by Iranian-backed militants in Lebanon, but some of the money is used to fund militia groups known as the Contras, which were trying to overthrow the socalist regime in Nicaragua. The revelation of the administration’s plan, which went against a Congressionally approved law banning federal money from being given to the Contras, becomes the biggest scandal of the Reagan presidency. The scandal becomes known as the Iran-Contra affair.
July 1988 – U.S. shoots down Iranian airplane
An American navy ship, the USS Vincennes, shoots down an Iranian civilian plane in the Persian Gulf, killing all 290 passengers and crew. The U.S. later apologizes and agrees to financial compensation for the victims families, saying the civilian plane was mistaken for an attacking military jet.
July 1988 – Iran-Iraq War ceasefire
Iran accepts United Nations Security Council Resolution 598, leading to a cease-fire in the Iran-Iraq War.
June 1989 – Ayatollah Khomeini dies
Khomeini, believed to be 89 years old, dies after having surgery for digestive system bleeding. After his death, an elected body of senior clerics — the Assembly of Experts — chooses the outgoing president of the Islamic Republic, Ali Khamenei, to succeed Khomeini as the national religious leader.
August 1989 – Hashemi Rafsanjani becomes president
Ali Akbar Hashemi Rafsanjani, the speaker of Iran’s parliament, is elected president. Rafsanjani was an influential member of the Council of Islamic Revolution of Iran in the Islamic Republic’s early days.
1995 – U.S. imposes broader sanctions
The Clinton administration expands sanctions that were put in place on Iran during the Iran-Iraq War, placing a complete oil and trade embargo on Iran. The U.S. accuses Iran of sponsoring terrorism, committing human rights abuses and seeking to sabotage the Arab-Israeli peace process.
1997 – Khatami elected president and Soleimani heads the Quds
Mohammad Khatami, who ran on pledges of political, social and economic reform, is elected as Iran’s president. This year, Gen. Qassem Soleimani also becomes the head of the Quds Force.
2000 – Reform candidates make gains
Pro-reform candidates and allies of President Khatami win a substantial number of seats in Iran’s parliament, setting the stage for reformers to control the legislature for the first time since the 1979 Islamic revolution.
2002 – “Axis of evil”
In his January State of the Union speech, U.S. President George W. Bush refers to Iran as part of an “axis of evil,” saying the country is actively pursuing weapons of mass destruction. The speech is met with anger in Iran. Iranian Foreign Minister Kamal Kharrazi responds by calling President Bush’s comments “arrogant” and saying Iran sees them as “interference in its internal affairs.”
2003 – Iran admits to plutonium production
The International Atomic Energy Agency says Iran admits to plutonium production, but the agency says there is no evidence that Iran is developing nuclear weapons. Iran agrees to more rigorous U.N. inspections of nuclear facilities.
2004 – Conservatives regain parliament
Conservatives reclaim control of Iran’s parliament after controversial elections that were boycotted by reformists.
2005 – Ahmadinejad becomes president of Iran
Mahmoud Ahmadinejad, the hardline Islamic mayor of Tehran, who campaigned as a champion of the poor and pledged to return to the values of the revolution of 1979, defeats one of Iran’s elder statesmen in presidential elections.
2006 – Ahmadinejad reaches out to Bush
Iranian President Mahmoud Ahmadinejad sends a letter to President Bush calling for ways to ease tensions over Iran’s nuclear program, but continues to defy U.N. deadlines to halt uranium enrichment activities. Ahmadinejad insists the nuclear program is for civilian energy purposes only.
2007 – Ahmadinejad visits the U.S.
Iranian President Mahmoud Ahmadinejad visits the United States and accuses Israel of occupation and racism during a speech to the U.N. General Assembly.
The United Nations announces new economic sanctions against Iran, targeted to impact the country’s military and halt Tehran’s disputed nuclear program.
A U.S. National Intelligence Estimate report finds that Iran stopped developing nuclear weapons in 2003, but continues to enrich uranium and could still develop atomic arms in the future.
2008 – IAEA calls Iran’s uranium enrichment a ‘serious concern’
The International Atomic Energy Agency releases a report saying Iran’s suspected research into the development of nuclear weapons remained “a matter of serious concern.” European Union nations agree to impose new sanctions against Iran.
2009 – Obama administration agrees to talks with Iran
The Obama administration announced it would participate in talks with Iran and the United nation’s five permanent members, breaking from the Bush administration. The talks eventually led to the Iran nuclear deal, also known as the JCPOA.
June – July, 2010 – U.S. and allies impose new sanctions
The U.N., U.S. and the European Union place further sanctions on Iran for its uranium enrichment activity.
June 15, 2013 – Rouhani is elected
Hassan Rouhani, who was described as a moderate, is elected president of Iran.
September 27, 2013 – Obama calls Rouhani
President Barack Obama called Iranian President Rouhani, which was the highest level of contact between the U.S. and Iran since 1979. The two discussed Iran’s nuclear program on the call.
January 2014 – Beginnings of a nuclear deal reached
Iran and the five U.N. permanent member nations reach an initial agreement regarding Iran’s nuclear program. In the coming months the first steps of that deal were implemented and negotiations for a more comprehensive plan continued.
March 2015 – Civil war breaks out in Yemen
Civil war breaks out in Yemen when a Saudi-led coalition launches airstrikes against Houthi rebels who have taken control of the capital city of Sana’a. The Houthis are supported by Iran, and Saudi Arabia, a U.S. ally in the Middle East, supports the Yemeni government. The U.S. sells weapons to Saudi Arabia, which are then used in the armed conflict. Five years later, the U.S. will try and fail to kill a senior Iranian military commander in Yemen the same day it successfully killed an Iranian general in Iraq.
July 14, 2015- U.S., Iran and other nations announce nuclear deal
Iran, the U.S. and the four other U.N. permanent members announce they have reached a comprehensive deal regarding Iran’s nuclear program. Iran agrees to limit its uranium enrichment and allow international inspectors into the country in exchange for the lifting of sanctions.
July 16, 2016 – Lifting of sanctions
The U.S. and Europe lifted sanctions on Iran as promised in the nuclear deal. The very next day, the Obama administration issued new sanctions against 11 people and companies with links to Iran’s ballistic missile program.
2017 – Trump extends sanctions waivers
The Trump administration renewed sanctions waivers that were part of the Iran nuclear deal.
May 8, 2018 – U.S. withdraws from the Iran nuclear deal
President Donald Trump announces the U.S. will withdraw from the Iran nuclear agreement and implements a “maximum-pressure campaign” in an attempt to force Iran to negotiate a new deal. In response, Iran says it will exceed the caps for uranium enrichment as outlined in the Iran nuclear deal. International nuclear watchdogs later confirm Iran has exceeded the limits.
April 8, 2019- Trump designates the IRGC a terrorist organization
The Trump administration announces it will designate Iran’s Islamic Revolutionary Guard Corps as a Foreign Terrorist Organization. It is the first time the U.S. declares part of another nation’s government as a terrorist organization.
May – October 2019 – U.S.-Iran tension ramp up amid attacks on oil tankers
A series of attacks on oil tankers near the Strait of Hormuz spark increased tensions between the U.S. and Iran. The U.S. blames Iran for attacks on oil tankers that were sailing under the Saudi Arabian, Japanese, Panamanian and British flags. In response, the U.S. attempts to seize an Iranian oil tanker.
November 2019 – Iranians riot over economic concerns
Over the course of four days, Iranians riot in the streets in opposition to an increase in oil prices. Amnesty International estimates more than 300 people were killed in the government’s crackdown on the demonstrations. The Trump administration sharply criticizes the Iranian government for how it handles the protests.
December 31, 2019 – Militia members attack U.S. embassy in Baghdad
Iraqi demonstrators and Iran – backed militia members break into the U.S. embassy in Baghdad and set fires in response to the American airstrike that killed members of an Iran-backed militia the previous weekend.
January 3, 2020 – U.S. kills Gen. Soleimani
U.S. kills Iran’s top general Qassem Soleimani as well as Iraqi militia leader Abu Mahdi al-Muhandis in a drone strike at a Baghdad airport.
January 8, 2020 – Iran strikes bases in Iraq housing U.S. soldiers
Iran launches missiles on two bases in Iraq where U.S. soldiers are stationed in retaliation for Soleimani’s killing; no casualties are reported. The same morning, a Ukrainian airliner crashes after taking off from Iran. A U.S. official says Iran shot down the plane with two Russian surface-to-air missiles.
January 9, 2020 – U.S. retaliates with sanctions
Trump announces his administration will impose new sanctions on Iran in response to the missile strike. The next day, Secretary of State Mike Pompeo and Treasury Secretary Steve Mnuchin outline the details of the sanctions, which target the construction, manufacturing, mining, and textiles industries. The sanctions also name eight Iranian officials.
January 11, 2020 – Iran admits it shot down a civilian plane
Layla Quran contributed to this story.