(Image - US and Iranian officials shake hands at the end of Vienna nuclear deal negotiations.)
US President Donald Trump called the Iranian nuclear deal signed during the Obama Administration an "embarrassment" as he stood before the United Nations General Assembly on September.
In response, Tehran's President Hassan Rouhani called Trump ignorant and warned that the deal should not be "destroyed by rogue newcomers to the world of politics".
This tit-for-tat approach to communication has long been a feature of Washington/Tehran relations. It's been a fraught relationship particularly since the fall of the Shah of Iran in 1979 when the Islamic movement forced him into exile and took control of the state.
The US's relationship with what was called Persia began benignly enough with the first real moves after the First World War when Tehran asked for financial aid in the wake of the conflict.
While political relations began much earlier, in 1856, both states were unknown to the other and full ambassadorial relations were only instituted in 1944 during the Second World War.
The relations were initially cordial and the Persians regarded the Americans as allies in their fight against the British and Russians, who had long involved themselves in Persian or Iranian affairs.
When Iran moved to break the stranglehold Russian and British industrial interests had in the country, they turned to American know-how during the 1940s. It was that close relationship that saw the Shah of Iran bolstered by American interests. The shah ruled from 1941 until he was deposed in 1979.
But it was the role of the Central Intelligence Agency (CIA) in an affair in 1953 that forever clouded relations between the US and Iran. The CIA has admitted it was behind a coup against Iran's democratically elected prime minister Mohammad Mosaddeq. That radicalised Iranians and led to the shah increasing his oppressive reign.
The CIA released a document in 2013 outlining its role.
"The military coup that overthrew Mosaddeq and his National Front cabinet was carried out under CIA direction as an act of US foreign policy, conceived and approved at the highest levels of government," it said.
Former US president Richard Nixon and the Shah of Iran (Presidential Library)
Mosaddeq had nationalised the British Anglo-Iranian Oil company, which became known as BP. That angered the British and the CIA worked with British Intelligence M16 to overthrow the democratically elected leader.
That has tarnished relations ever since, with the shah regarded as a US puppet. When he was banished in 1979 he fled to the US with his family.
Then Iranian students took the staff of the American Embassy in Tehran hostage and held 52 American diplomats and citizens hostage for a total of 444 days from November 4 1979 to January 20 1981.
During that time, the US launched a botched invasion by its special forces to try to secure their release. Operation Eagle Claw was ordered by then US president Jimmy Carter but ended in failure and humiliated the Americans. On April 24 1980, the mission failed due to a combination of weak planning, logistics mishaps and poor training.
US president George Bush senior welcomes Iran hostages home
Eight Americans died and a helicopter crashed into a transport plane at an improvised airfield inside Iran. Iranians were incensed and US interests were further damaged by this incursion.
Iran has steadily been building a nuclear industry despite US attempts to stop them for decades with Tehran announcing it would continue to build a nuclear capacity as its enemies, both the US and Israel, already have such weapons.
Rouhani addressed the UN General Assembly on September 20 2017 saying it “will not be the first country to violate the agreement, but it will respond decisively and resolutely to its violation by any party".
Iran has a ballistic missile programme running concurrently with its nuclear programme and despite claiming it is not actively building nuclear weapons, CIA and other intelligence reports indicate Tehran is indeed building a nuclear capability which the agency says has military implications.
