Ayatollah Ali Khamenei and Hassan Rouhani. Photograph: AFP/Getty Images  There is a new willingness to settle the Iranian nuclear question. But success depends on absorbing lessons from the years of failed efforts. Fortunately, nearly all are being addressed.  First, work to dispel distrust. This has fixed the negotiators in maximal positions, limiting offers which, when rejected, confirm the perception that the other side is not serious.  The early signs are good: Barack Obama and Hassan Rouhani have instilled hope for a new start in the multilateral talks and for a secret bilateral US-Iran channel alongside them. Ayatollah Ali Khamenei has talked of the value of "heroic flexibility" in the negotiations. The White House is telling the US Congress that imposing new US sanctions against Iran now would be wrong.  Second, don't ask for too much. There has been a habit of over-bidding, demanding ideal solutions while letting proposals that would be effective and should have been acceptable die for lack of effort.  At the meetings in Geneva in mid-October the aim will be to deal with the immediate concerns of the six world powers involved. These concerns include 20% enrichment, stocks of both 3.5 and 20% enriched material, and the potential of the underground Fordow plant for making military-grade uranium if Iran went quickly for a bomb. In return, Iran expects more sanctions relief than it was offered in the Almaty talks in the first half of the year.  The six world powers – Britain, China, France, Germany, Russia, the United States – will be cautious about paying a lot for Iranian concessions, such as suspending some EU financial and oil sanctions, for fear that they will have too little leverage left for the negotiations on a final deal next year. Iranian negotiators have to keep in mind demands from others in the Iranian system that concessions should only be granted in return for the lifting of all sanctions.  Third, don't pursue ambiguous policies. The west and Israel have damaged themselves in Iranian eyes by saying they have no quarrel with Iranians as a people and then through oil and financial sanctions hammering the Iranian economy into recession. Iran has offered useful concessions, for example capping uranium enrichment at 5%, but has too often negated them within frameworks involving up-front concessions to Iran on sanctions that went far too far to be negotiated at that time.  Fourth, project unity. The six have failed to project unity on their negotiating objectives. China and Russia prefer a phased deal ending with Iran having a normal but strictly supervised civil nuclear programme including enrichment geared to the fuel requirements of Bushehr and future power-generating reactors. The west has been tentative about such ideas while seeking suspension of enrichment by demanding that Iran adheres to UN security council resolutions.  So Iran has yet to be convinced that it will ever be treated in the same way as other enrichment-capable countries, such as Brazil or Argentina, however much it agrees to limit its programmes. The first signs of a change emerged in response to the forcefulness and clarity with which Rouhani and the foreign minister, Mohammad Javad Zarif, presented their case. The rest of the six may be coming round to Russia and China's position - that at the start of the process Iran should be given assurances on what its nuclear programme could look like at the end if Iran does what is asked of it.  The problem of unity that the Iranians have is about the divisions in the Iranian establishment. During the Ahmadinejad era, this provided opponents in the west with an excuse for rigidity. Rouhani and Khamenei have dispelled this for now. The domestic political conditions in Tehran have never been as propitious for a settlement as they are today.  That leads to the fifth lesson: empower your envoys. In the past, Iranian envoys have been outflanked by those at home who cry betrayal of the revolution. Among the six, suspicion of Iran and Israel-handling sensitivities have limited the flexibility given to their representatives. It is most encouraging that it was agreed in New York to entrust the Iranian and US foreign ministers with the lead in the talks, and to meet in Geneva as often as necessary.  The sixth obstacle has been lack of belief that the problem can be solved. There is little positive to say about this yet – the new initiative has scarcely begun. The US and EU have been unwilling to take risks and spend domestic political credit in the advocacy of new ideas, especially in the face of entrenched lobbies. One still hears some say that the best that can be hoped for this time is a first-stage agreement that kicks the can down the road.  Israel doubts that any negotiated settlement can meet its requirements. This is a challenge. Russia, China and European countries that have different interests and different views must make their voices heard publicly and privately in Washington, Jerusalem, Riyadh and Abu Dhabi. Their own public opinion, as well as opinion in the US, is clearly in favour of giving diplomacy a proper chance.  But diplomacy with what outcome? Debate on what would be a safe or unsafe Iranian capability has begun. It will be the detail that will count in permitting all involved to decide whether the risks have been reduced far enough to sign up to a deal.  The negotiations should be held by the participants in confidence, but there needs to be public debate on these apparently technical details in order to strengthen the belief that solutions that protect the region and the non-proliferation treaty can indeed be found.  Finally, neither side has tried to alleviate the security concerns of the other. Israel, Gulf states, the US and Iran all have justifiable fears of potential threats.  Fortunately, the old US insistence that Iran should simply be forced into line is slowly giving way in Washington. Iran may renew the approach it made to the US in 2003 for a wide-ranging discussion of regional issues. The response this time, I believe, would be to work with Iran, not to ignore it.  • Sir Richard Dalton is associate fellow on the Middle East and north Africa programme at Chatham House, and a former British ambassador to Iran (2002-06).
Problems of distrust, overbidding, ambiguous policies and lack of unity on both sides have hampered talks in the past