Neither side comes off well in this blow-by-blow account of an international spat.
US President Donald Trump might decertify the pact to curb Iran’s nuclear programme on Friday.
But as the nuclear deal turns two years old, we have to ask: how did we get here?
1953 – Iran's Premier Mossadegh overthrown
British and American intelligence agencies orchestrate a coup d’etat to oust the Shah's appointed Prime Minister, Mohammad Mossadegh.
The coup is intended to rout Mossadegh’s policy of nationalising the country’s oil industry, which had been under British control since 1913 through the Anglo-Persian Oil Company – or British Petroleum, as it is known today. The ouster also aimed to stop encroaching Soviet influence in Iran.
With strong military and economic backing from Washington, the notoriously profligate Shah Mohammad Reza Pahlavi returns to power, ruling the country until the Islamic Revolution in 1979. The Pahvlavi dynasty itself was installed by the British Empire after in a coup orchestrated in 1921.
1977– US President Jimmy Carter takes office. He sets about building a unique relationship with Pahlavi, who had accepted the role of protecting US interests in the country.
1979 – The Age of Ayatollahs
The US-backed Shah is forced to leave the country following months of clashes and clerical revolts against his puppet regime. He travels through various countries until heading to the US for cancer treatment.
Following his departure, Iranian religious leader, Ayatollah Khomeini returns from exile in France to take power in Iran. Thousands of cassette recordings were heard across the country.
In public, Khomeini voices rhetoric against the US and Carter for their support of the Shah. He soon becomes the charismatic leader of the opposition.
The tapes hide a truth: Khomeini privately assures the US of his support in ongoing contact with the US. The Carter administration effectively paves the way for his return to Iran, sending a general to keep the military from a takeover.
After Khomenei's return, political and social instability escalated and street battles raged between pro-Khomeini protesters and security officers across the country.
'Islamic Republic's' birth
In April - A national constitutional referendum asks voters this question: "Age-old [monarchial] regime change to Islamic republic, the constitution of which will be approved by the nation – Yes or No?"
Following a landslide victory, Khomeini declares the country an Islamic republic. It is "God's government" he says, and to stand against him would be a "revolt against God." After initial struggles with leftists, power is placed squarely in the hands of a clerical class, by way a controversial doctrine known as Wilayet e faqih. The doctrine later shapes the autocratic nature of the Republic's rule.
Khomeini becomes Iran's political and religious Supreme Leader, a role he holds for life.
One of his first moves was to publicly back the seizure of US hostages, by sending his son to the embassy.
In November, a watershed event began that broke diplomatic relations between the two nations. Iranian students fiercely loyal to Khomeini seize the US embassy in Tehran and take 90 hostages, including 52 who were held captive for 444 days. They demand the expulsion of the Shah from the US.
The majority of the students go on to serve in senior government positions.
It remains the longest-running hostage crisis in recorded history.
Following the crisis, Carter severes diplomatic ties with Iran and signed an executive order to freeze all assets, properties, and bank accounts of the Iranian government in the US.
1980 – A Carter-led hostage rescue mission fails after helicopters crashes in a sandstorm and eight US servicemen were killed.
1981 – Iran releases hostages one minute after the US President Reagan was sworn in, a move seen as punishment for Carter's support of the Shah.
Iranian proxies wage suicide attacks
1983 – Iran-backed Hezbollah orchestrates suicide bomb attacks against US embassies and American marine barracks in Beirut that killed over 258 Americans, including 241 military personnel.
1984 – Washington designates Iran as a state sponsor of terrorism.
1985-1986 – Reagan admits to a secret arms deals with Iran that broke a US embargo. The trade was aimed at winning the release of Americans held by pro-Iranian Shia Muslim militants in Lebanon. Money from the sales was secretly passed to US-backed Contra guerrillas who attempted to overthrow the left wing government in Nicaragua.
1987 –The US weighs in on the Iran-Iraq war, launching Operation Earnest Will to escort Kuwaiti oil tankers after the war spilled over into the waters of the Persian Gulf. Iran attacks any tanker of the Gulf states that supported Iraq in retaliation.
1988 – The US launches Operation Praying Mantis in the Persian Gulf after its guided-missile frigate USS Samuel B Roberts was severely damaged by Iran during the Iraq-Iran war.
It was the largest surface naval battle with Iran since World War II.
In the one-day operation, Americans sink two Iranian vessels and oil platforms.
Death of pilgrims
Pilgrims In July – US warship Vincennes, mistakenly according to the US, shoots down an Iranian passenger plane over the Gulf, killing all 290 people on board. The plane was loaded with Iranian pilgrims who were on their way to Mecca.
An era of 'reform'?
1997 – Iranian voters sweep President Mohammad Khatami to power. He was billed by some as reform-minded for his call for "a dialogue with the American people" in an interview with a US TV channel.
2001 – Following the 9/11 attack, Iran publicly cooperates with the US against the Taliban in neighbouring Afghanistan. In practice, it harbours Al Qaeda for several years, allowing the group to operate from Iranian soil.
'Axis of evil'
2002 – In October, in his State of the Union address to the US Congress, President George Bush declares Iran, Iraq, North Korea part of an “axis of evil,” accusing them of operating secret nuclear weapons program.
In August – An exiled opposition group called, Mujahideen e Khalq reveals Iran's secret nuclear programme. The group exposes the existence of the enrichment plant in Natanz and the heavy-water plant in Arak.
2004 – Iran publicly agrees to halt enrichment temporarily after 22 hours of negotiations with the senior officials from France, Germany and Britain.
2006 – Mahmoud Ahmadinejad takes office and the country resumes uranium enrichment.
2006-2010 – Iran is hit with four rounds of UN Security Council sanctions between 2006 and 2010 for refusing to halt its nuclear enrichment program.
2013 – Iran elects Hassan Rouhani as president on a platform of improving Iran’s relations with the world and its economy.
In September – US President Barack Obama and Rouhani speak over the telephone. It is the highest-level contact between the two countries in three decades.
The two leaders express their determination to solve the long-running dispute over Iran's nuclear programme.
In November – Iran and six major powers , the US , Britain, China, France, Germany and Russia, reach an interim pact called the The Joint Comprehensive Plan of Action (JPCOA). Iran agrees to curb its nuclear work in return for limited sanctions relief.
2015– Iran and the six powers strike an agreement, under which Iran agrees to take a series of steps, including slashing its number of centrifuges and disabling a key part of its Arak nuclear reactor – in return for significant easing of US, UN and EU sanctions.