During the last round of nuclear negotiations between Iran and the US in Vienna, the shouting and hurling of accusations by US Secretary of State John Kerry and his Iranian counterpart Mohammad Zarif became so loud it could be heard from adjoining rooms. They were eventually asked by their aides to keep it down. The US accused the Iranians of supporting terrorism overseas, while the Iranians accused the US of war crimes for propping up the regime of Saddam Hussein during the Iran-Iraq war.

The relationship between Iran and the US is a tale of treachery. They have needed this showdown for a long time because their relationship is no ordinary one. It is a story of betrayal; each believed in the other and each feels the other let them down at crucial moments.

It all started with an accountant in 1911.

Actually it began before that, when an American named Howard Baskerville went to Iran and commanded a small band of Iranian rebels during the Iranian constitutional revolution in 1909. He died for the cause, shot through the heart by a sniper, but his passionate belief in Iran's right to democracy was something future Americans were also to demonstrate.

The accountant Morgan Shuster was appointed by the Majlis as State Treasurer in 1911 to help them manage the large debts the Qajar dynasty had accumulated with the imperial powers, largely Russia at that point. Russia and Britain forced the Iranians to expel Shuster after only six months, whereupon he returned to the US and wrote a book entitled The Strangling of Persia, which criticised the imperial ambitions of Russia and Britain, whom he accused of thwarting Iran's chances of becoming a democracy.

Shuster was succeeded in 1922 by Arthur Millspaugh, whom Reza Shah invited to Iran to continue the work of Shuster. He was able to institute a tax system and assist in straightening out the state's finances. Others followed: Samuel Jordan established a boys school and Arthur Pope fell in love with Iranian art, writing a six-volume survey on the topic and assisting the Shah in restoring exquisite historic buildings in Isfahan and beyond.

For a long time Iran turned to America to help free it from its imperial overlords, particularly Russia and Britain, until the fateful Mossadeq Affair in 1953, which constituted the initial breach of trust between the two countries. Later events hardened attitudes on both sides; Mohammed Reza Shah tried to play the Americans over oil prices, a tactic which ended in disaster when the US changed tack and began to ally more closely with the Saudis (something Andrew Scott Cooper details superbly in The Oil Kings). The final blow was struck during the 444 days of the American hostage crisis. Thereafter, the bitterness set in.

So why is Iran now bothering with the US again? It is because Iran has always craved influence regionally and internationally. Iran needs to be given a seat at the table, for so long as it has been denied one it has used asymmetric tactics to bolster its position.

Iran is an outsider in its own neighbourhood. The states on its borders have a different ethnicity, language and, to the northwest, a different religion. It's well known that under the Shah, Iran had dealings with Israel to alleviate its regional isolation. Iran's closeness to the US prior to the revolution was not just about oil and weapons; Iran needed powerful friends because it has no natural allies on its borders or within its region. This is still the case, and reaching out to China or Russia will not afford Iran the status it craves (moreover, in the case of Russia there are good historical reasons for not wanting to risk future interference). This is why President Rouhani was allowed by Ayatollah Khamenei to reach out to Obama, something Rouhani would not have done without permission from the Supreme Leader.

That these two states have managed to conduct negotiations face-to-face at all – let alone successful ones — is an achievement. But as Anthony Bubalo notes, implementing the deal will prove the most difficult part.

In the meantime, Iran is already changing as a result of the deal. It is rumoured that Iran is planning to revise its visa regulations for foreign visitors to open up the country to tourists who now regard it as safe to visit. And the British have announced they will re-open their embassy, possibly by the end of the year.

The deal may well set the stage for negotiations on other issues. I am curious to see how the US-Iran relationship evolves beyond the nuclear deal, if it's possible to get past the tired 'Iran threat' rhetoric already being spewed by Republican Presidential candidates, Israel and others.

Iran has some right to a more prominent international role. It is one of the largest, most populous states in the Middle East, has large untapped gas resources, and has one of the most highly educated populations (both men and women) in the region. This deal offers Iran the political and economic opportunity to demonstrate it can operate as a responsible international stakeholder.

Photo by Flickr user EEAS.