Iran president Mahmoud Ahmadinejad said; 'The Iranian nation is standing firm on its fundamental rights.' Photograph: Iranian President's Office/AP
The US has warned Iran that it will be expected to "demonstrate verifiably" at talks in Istanbul this weekend that it is prepared to roll back its nuclear programme.
The White House has said that "the window was closing" for Tehran to reassure the six countries present at the talks – the US, Russia, China, Britain, France and Germany – that it is not using the negotiations to buy time.
The US secretary of state, Hillary Clinton, reinforced that message on Thursday when she said that in order for the talks to continue Washington is "looking for concrete results" from Iran to show that it is not in pursuit of nuclear weapons.
"We want them to demonstrate, clearly, in the actions they propose that they have truly abandoned any nuclear weapons ambition," she said. "Of course, in a negotiation, we understand that the Iranians will be asking for assurances or actions from us and we will certainly take those under consideration."
Western officials say Washington is committed to its ultimate goal of seeing Iran dismantle its fortified underground nuclear facility at Fordo and hand over higher grade enriched uranium – moves also demanded by Israel, which is threatening a military assault if Tehran's nuclear programme continues to advance, although there is no firm evidence it is developing a nuclear weapon.
But first, the US, backed by the Europeans, is looking to Iran to demonstrate that it is serious after the last round of negotiations in January 2011 collapsed when Tehran demanded that sanctions be dropped and the major powers recognise its right to enrich uranium before negotiations could proceed.
"We're not setting in advance of this meeting any condition except for what our bottom line is, and that's a bottom line shared internationally," said the White House spokesman, Jay Carney. "The Iranians need to demonstrate that they are serious, that they will engage in these talks seriously and focus on the issues that need to be resolved. Beyond that, we'll have to see how they go."
Officials in Washington acknowledge they have little idea as to how Iran will respond.
Tehran says it will present "new initiatives" in Istanbul but it has given no details.
President Mahmoud Ahmadinejad said on Thursday that his country will not retreat on its nuclear programme.
"The Iranian nation is standing firm on its fundamental rights and under the harshest pressure will not retreat an iota from its undeniable right," he said. But the ultimate decision lies with Iran's supreme leader, Ayatollah Ali Khamenei, who has said the pursuit of nuclear weapons is un-Islamic.
"The Iranians are under no illusions," said one western official. "The emphasis is on them to demonstrate they are serious about the talks. We need to come out of it convinced that a second meeting is worthwhile."
Barack Obama needs to demonstrate that sanctions and diplomacy are having the desired effect on Tehran in order to stave off pressure from Israel and Republicans in Congress who have already declared them a failure and are pressing for a more robust – which to many means military – response.
But the major powers at the table cannot themselves agree what constitutes progress. The Europeans have pushed even harder than the US for pressure to be brought to bear on Tehran. The Russians and the Chinese have supported four UN security council resolutions demanding that Iran stop enriching uranium, but they have opposed the biting oil and banking sanctions against Tehran and argued for incentives to encourage Iran.
Moscow has held direct talks with Iran that were intended to agree a plan in which US and European sanctions were gradually eased as Tehran opened up to international oversight of its nuclear programme. But the negotiations were inconclusive.
Sergey Ryabkov, the Russian deputy foreign minister, said in Washington this week that there is no common position in confronting the Iranians at the talks. "I do not think that we'll come to any unified position before the negotiations, but rather have a menu of options," said Ryabkov.
The Americans and Europeans say that the clearest demonstration that Tehran is serious would be for it to immediately stop enriching uranium to a higher grade than is required for power stations.
Iran is enriching uranium at its fortified underground facility at Fordo to 20%.
Electricity plants run on uranium refined up to 5%. A bomb requires 90% but the leap from 20% is relatively easy. Iran says it needs 20% refined uranium to fuel a medical isotope reactor.
"We would look to a freezing of the 20% enrichment right at the beginning," said one official in Washington. "But we're not being prescriptive. That could be something for a second round if we walk out the door knowing that Iran is serious. There's not many people around here who are holding their breath on that one."
The stated aim of the pressure is to get Iran to cease all enrichment. But the US and Russia have hinted at agreeing to Tehran enriching its own uranium for use in power plants – a retreat on their original demands that nuclear rods had to be imported by Iran. However, Ryabkov said the "right to enrich (is) not an opening negotiating proposal, let me be clear".
Dennis Ross, Obama's former national security council adviser on Iran, this week proposed that Iran be permitted to conduct limited enrichment. But Ross said that it would be necessary to reach an interim agreement first that "stops the clock" on Iranian nuclear advances in order to reassure Israel and hold off the threat of military action.
"The advantage of the interim approach is that it could buy time and space to reach more fundamental understandings. The disadvantage is that it does not solve the problem and may take the pressure off Iran in a way that would not be so easy to resume later. In short, an interim step that stops the momentum toward the use of force would be desirable but also risky, since that momentum may be the very thing spurring Iran's interest in finding a way out," wrote Ross.
The latest talks were prompted by a letter from the Iranian leadership to the EU's foreign affairs chief, Catherine Ashton, in February that was initially met with scepticism. But Tehran's promise to bring new initiatives to the table and the Obama administration's need to see diplomatic pressure in order to stave off pressure from Israel and the US Congress saw the talks agreed.
