Path to nuclear power

Iran's nuclear program got its start under the shah in the 1960s. At the time, the US had advised him to make the switch to nuclear, despite the country's vast oil and gas reserves. Iran's first research reactor went online in 1967, with major systems built thanks to help from Germany and France. But the Iranian Revolution in 1979 put an end to any further Western involvement.

In 2002, the international community discovered Iran's nuclear program when the International Atomic Energy Agency (IAEA) released intelligence information on uranium enrichment plants in the city of Natanz and a heavy water reactor in Arak. Shortly thereafter, IAEA inspectors found traces of enriched uranium, triggering a political crisis.

The United Kingdom, France and Germany began talks with Iran, and the country eventually agreed to suspend its enrichment activities in return for trade facilitation from Europe. But the agreement was short-lived: In 2004, the Iranian government once again refused IAEA inspections and information requests.

Hardliners lead to isolation

With the election of President Mahmoud Ahmadinejad in 2005, Iran toughened its approach. Tehran insisted on its right to the peaceful use of atomic energy and the international exchange of knowhow and material, just like other countries.

But the US chose to exclude Iran from this exchange, which led the regime to find what it needed elsewhere, including from Abdul Qadeer Khan, the father of Pakistan's atomic bomb. That same year, Iran 's spiritual leader Ayatollah Ali Khamenei issued a fatwa banning the production, possession and use of nuclear weapons.

But Ahmadinejad continued with confrontation when, in 2006, he removed the IAEA's inspection seals from the Natanz uranium enrichment plant. He also announced that Iran, for the first time, had closed the nuclear fuel cycle and produced fissile material.

Condemnation from the UN Security Council

With Iran steadfastly refusing to allow comprehensive inspections, the IAEA finally referred the issue to the UN Security Council. In December 2006, the UN decided on the first sanctions which the EU subsequently intensified. The list included travel bans, an embargo on arms, material related to nuclear production and telecommunications, as well as a ban on investments in the oil and gas industry. Direct financial assistance was also prohibited.

By the fall of 2008, a total of five UN resolutions had been adopted calling on Iran to put an end to its nuclear development activities and allow inspections. Tehran brushed them all off, and continued to develop its nuclear program.

News of the construction of the enrichment facility at Fordo caused an international uproar. The complex, located deep underground near the holy city Qom, is well protected against military attacks. The reason for this being that at the time, Israel had already bombed Iraqi and Syrian aboveground plants. Once again, the IAEA requested free access for its inspectors and for work at Fordo to be halted.

At the time, sporadic negotiations with Iran were undertaken by the EU3+3 - also known as the P5+1 group - which consisted of the original European partners and permanent UN Security Council members USA, Russia and China. Talks remained formal, and were completely unsuccessful. Israel threatened several times to strike with its military forces against Iran's nuclear facilities.

In 2012, the United Nations made two more resolutions and decided on additional sanctions against Iran's oil industry and the financial sector. The West also demanded Fordo's closure, but Iran refused to give in. As a result, even more restrictions came into force, hitting the banking sector, commodities trading, gas exports, shipping and air freight, largely isolating Iran from international markets.

Struggling economy leads to change

It wasn't until after the election of President Hassan Rouhani in the summer of 2013 that negotiations got back on track. However, it soon became clear that the situation had changed. In the eight years Ahmadinejad was in office, uranium enrichment in the original 100 centrifuges had been expanded to around 19,000 in three separate plants.

Also subject to dispute: Iran's ability to produce uranium enriched to 20 percent, the threshold for weapons-grade material. Today, experts believe Iran could build a nuclear bomb within three months. The US aim is to reduce the amount of fissile material in the country to the level that this period is extended to one year.

Rouhani is pushing for an agreement, so that sanctions can be lifted. The Iranian economy is in tatters, and the country is threatened by bankruptcy. Last November's agreement in Geneva established a framework for the continuation of negotiations: Under a six-month moratorium, Iran was to suspend uranium enrichment. During this time, both sides had hoped to sign an agreement which would exclude military use of nuclear power in Iran and allow for a lifting of sanctions.

As a sign of goodwill, the EU eased some of its sanctions and US President Barack Obama made his first direct contact with Iranian leadership. Rouhani has insisted that he wants to improve relations with the West. But hardliners back home are breathing down his neck, and Ayatollah Khamenei, Iran's silent ruler, will always have the last word.