Expectations are low as Iran begins a new round of nuclear summitry with six leading world powers in Istanbul today.
Sir Richard Dalton, Britain's former ambassador to Iran, said: "Neither the US nor Iran sees it in their interests to shift at the moment."
However, the threat of an Israeli or US military attack on Iran's nuclear facilities if negotiations break down or drag on has receded in recent weeks, allowing vital breathing space for further diplomacy.
That is a huge relief for a region already jittery over the tumultuous events in Tunisia and fearful of renewed instability in Lebanon. A military adventure against Iran could unleash a regional war.
The major western powers believe their hand has been strengthened recently. The Obama administration claims that Tehran's nuclear trajectory has been set back by sweeping sanctions that are inflicting economic pain on the regime and reportedly are thwarting its ability to acquire vital materials for enriching uranium.
In addition, The New York Times claimed this week that a cyber-weapon called Stuxnet, deployed jointly by American and Israeli experts, has yanked back the hands of Iran's atomic clock.
Meanwhile, recent Israeli intelligence assessments say the Islamic republic will not be able to build a nuclear weapon before 2015 at the earliest. That is three or four years later than previous Israeli estimates.
All told, these new evaluations of Iran's nuclear setbacks have "lowered the temperature on what had been 2010's hottest strategic issue", David Ignatius, a Washington Post columnist, wrote earlier this month. "Last summer Jerusalem and Washington were talking themselves into a war fever."
Iran, which insists its nuclear programme is a peaceful drive to generate electricity, appears no less confident going into the two-day talks in Istanbul, which bring together Iran and the so-called P5+1, comprising the five permanent members of the UN Security Council - the US, Russia, China, France and Britain - and Germany.
Tehran maintains that its nuclear activities are progressing swiftly, that sanctions are a damp squib and, while acknowledging that Stuxnet infiltrated its uranium enrichment facility at Natanz, claims the damage was minimal.
Tehran's UN envoy, Mohammad Khazaee, said on Tuesday that Iran must be accepted as a "heavyweight champion in the region" and would not negotiate with a "knife in the neck".
Many analysts believe the most the West can expect in Istanbul is to resurrect a 15-month-old confidence-building measure on Iran's stockpile of low-enriched uranium (LEU) which, if successful, could help to rebuild its ragged relationship with Tehran.
The last round in Geneva six weeks ago produced nothing significant, apart from resuming a dialogue after a bad-tempered, 14-month hiatus.
Mutual suspicion runs deep. The West fears that Iran will filibuster while pressing ahead with its nuclear programme. Tehran, in turn, suspects the West is going through the diplomatic motions while it waits for sanctions to force an Iranian compromise. The US secretary of state, Hillary Clinton, said this week that the US "may be proposing more unilateral sanctions".
Both sides want to talk about different issues. Iran is pushing an agenda that covers just about everything except its nuclear programme: global disarmament, Israel's undeclared nuclear weapons arsenal, fighting terrorism and co-operation on Iraq and Afghanistan.
Iran's nuclear ambitions are, however, the P5+1's focus of concern. Iran pressed hard for this round of talks to take place in Turkey, which has developed close economic and political ties with Tehran. Turkey and Brazil, along with Lebanon, were the only countries on the UN Security Council that voted against a fourth round of sanctions against Iran last June.
The confidence-building measure set to feature prominently in Istanbul entails Iran surrendering the bulk of its LEU in exchange for foreign-made fuel rods for a medical research reactor in Tehran.
The deal, theoretically, would benefit both sides. Iran would get fuel for its reactor and the West would ensure Iran's LEU stockpile is reduced below the amount needed to produce a nuclear weapon. And, vitally, from Iran's viewpoint, such an accord would tacitly accept its uranium enrichment programme.
Western officials say the deal needs to be updated because Iran's LEU stockpile has doubled since the accord was first mooted in October 2009.
But Iranian nuclear officials warn that time is running out for the West because Tehran will soon be able to manufacture its own fuel rods for its medical reactor. In that case, it will be difficult to persuade the Iranian parliament to agree to allow any transfer of uranium abroad, they say.
Farideh Farhi, a leading Iran analyst, said: "The way it looks, Iran is entering the talks in the hope of making the best out of a weak hand, this time generated by the much-publicised argument that Iran's nuclear programme has faced setbacks both because of espionage and sanctions."
Other Iran experts believe Iran feels no weaker going into today's talks. Sir Richard, now a fellow at Chatham House, a leading British think-tank, said: "Some of the fuss about Stuxnet seems to be bluster by the US and Israel. They created a programme which may have crashed only a small proportion of Iran's [5,000 uranium enrichment] centrifuges."
He believes sanctions on exporting materials and equipment are having a more potent effect. "Sanctions are always a long-term strategy and what we're seeing now is the effectiveness of sanctions adopted some time ago," Sir Richard said.
Gary Sick, a leading Iran expert at Columbia University in New York, said: "It's hard to believe anything's going to happen of any great significance [in Istanbul]. But if the US insists that every bit of Iran's LEU has to be out of the country then I expect progress will be very, very slow."
Iran's bottom line has always been that it has the right to continue enriching uranium on its own territory under international safeguards.
Claims of Stuxnet's vaunted prowess, meanwhile, probably have more to do with US politics than the virus's real potency, Prof Sick said. Mr Obama can now placate his domestic critics, who were pressing for tougher action against Iran, by arguing that Washington has worked with Israel to set back the alleged Iranian nuclear threat.
"If you're running for re-election, that's a terrific line. But did it really change Iran's determination to build an independent nuclear programme? Not a bit," Prof Sick said.
Meir Javedanfar, an Iranian-born analyst based in Israel and co-author of The Nuclear Sphinx of Iran: Mahmoud Ahmadinejad and the State of Iran, said the chances of an Iranian compromise may have been higher if the Stuxnet virus had "managed to destroy more than 50 per cent of Iran's centrifuges".
But, he added, the longer the stalemate continues, the more it will play into American hands as sanctions bite deeper and Iran becomes more internationally isolated.
"The Iranians have always played the long game," Mr Javedanfar said. "But it seems the Obama administration is now playing the long game and doing it better than the Iranians."
