Relations have soured since Trump withdrew from the Iran nuclear deal last year. The deal, also known as the Joint Comprehensive Plan of Action, was agreed by the Obama administration in 2015 and was signed by the US, Iran, China, Russia, the UK, France and the EU. It was agreed that Iran would limit its nuclear activities and allow international inspectors to examine its nuclear sites in return for the lifting of crippling economic sanctions.
However, Trump announced in May 2018 that the US would withdraw from the deal and in November Washington reintroduced sanctions on Tehran.
Despite threats from the US, the other countries remained in the agreement and the deal appeared to be otherwise intact – until this month when Iran announced partial withdrawal as a “reciprocal measure”.
Iran also announced it had quadrupled its production capacity of low-enriched uranium.
Tehran insists that uranium will only be enriched up to the 3.67 percent limit set under the deal, but the stockpile will soon exceed quantity limitations.
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US President Donald Trump and Iranian President Hassan Rouhani
President Obama meets with veterans to discuss Iran nuclear deal
It has also given an ultimatum that unless new terms are set by July 7, it will enrich close to weapon-great levels.
Meanwhile, the UAE has alleged that four oil tankers were sabotaged off its coast and that Iranian-allied rebels in Yemen have launched drone attacks in Saudi Arabia.
The US meanwhile sent an aircraft carrier and B-52 bombers to the region over a perceived threat from Iran.
However, the history of poor relations and mistrust between the US and Iran are more than just about this nuclear deal and date back over 40 years.
Donald Trump has reintroduced sanctions on Iran
Shah of Iran
Before the revolution in 1979, Iran was ruled by the US-friendly Mohammed Reza Shah, propped up by the West.
The Shah originally took over from his father, who was pushed into exile in 1941.
In 1953, he was ousted by supporters of Prime Minister Mohammad Mosaddeg, but the US and UK orchestrated a coup against the government and reinstated the Shah.
The Shah went on to launch the White Revolution, which upended the wealth and influence of landowners and clerics, disrupted rural economies and heavily westernised Iran.
Opposition to his rule bubbled up in the Seventies and protests began in 1978.
The Shah responded harshly and many were killed in demonstrations, which only spurred people on as protests escalated and many workers went on strike.
In 1979, the Shah and his family fled Iran and Ayatollah Khomeini, previously in exile, declared Iran an Islamic Republic.
When the Ayatollah returned, he called for the expulsion of all foreigners and the US State Department evacuated 1,350 Americans.
Iranian Revolution 1979
Khomeini said: “I beg God to cut off the hands of all evil foreigners and their helpers.”
Conservative Islamic social values returned and the militias and clerics suppressed all Western cultural influence.
Meanwhile, the Shah went to the US and underwent treatment for cancer.
Anti-Western sentiment in Iran grew stronger and in November 1979 protestors seized 66 hostages in the US embassy and demanded the extradition of the Shah.
Hostage crisis 1979
US President Jimmy Carter
In 1980, President Jimmy Carter attempted to rescue the hostages, but the mission failed and eight US commandos were killed.
Although the Shah died in Egypt, the hostages were still not released and the captors now demanded other concessions.
A spokesperson for the Iranian president Abul-hassan Bani Sadr said: “For us, he has been dead for years.”
The hostages remained in captivity for 444 days until the US agreed to release frozen Iranian assets and promised not to interfere in Iran.
However, in 1986 Ronald Reagan admitted to Congress sending “small amounts of defensive weapons” to Iran in what has since been dubbed the Iran-Contra affair.
While it was claimed this was on a small scale, scandal hit when it was discovered that millions of dollars were being diverted from Iranian arms sales to Nicaraguan rebels.
The President and Vice President claimed they had no knowledge of these fund diversions, though.
In 1987, the US intervened in the Iran-Iraq war, protecting certain shipping, sinking several Iranian ships and also accidentally downed an airliner before the UN brokered peace in 1988.
In 1991, the US intervened in the Middle East again after Iraq invaded Kuwait during the Gulf War, striking in Baghdad and other targets and declining Iran’s offer to mediate.
Iran and Russia signed a nuclear contract in 1995 – and in 1996 President Clinton imposed sanctions in the fight against “terrorism”.
In 2002, secret nuclear facilities in Iran were discovered and in 2004 it agreed to temporarily halt uranium production.
However in 2006, Iran resumed uranium enrichment at Natanz after negotiations with the US and EU stalled and the US proposed a top-secret cyberwar programme against Iran, while the UN imposed sanctions.
US troops arriving for the Gulf War in 1990
George H W Bush greets US troops during the Gulf War
The second Gulf War – started by the 2003 invasion of Iraq and deposition of Saddam Hussein – left Iran as the major threat in the Middle East.
During the Obama administration, the US pushed for Iran to allow international inspection of its nuclear sites, while the UN ramped up sanctions.
Eventually, talks culminate in the Iran nuclear deal, which many hailed as victory.
However, President Trump claims Iran had no intention of sticking to the terms of the agreement and the US currently perceives Tehran as the most urgent nuclear threat in the world.