BRUSSELS/LONDON The talk can be blunt and the rhetoric can be flowery, with invocations of deity and Persian poetry. Sometimes, it has been suggested, there is the sense of a well-worn cast acting out a script.
Iran's negotiations with the West on its nuclear programme have developed their own rituals and etiquette bound up with the frustrations of a decade of fruitless talk. Sheltering from a Baghdad sandstorm or esconsed in a drab communist-era Moscow hotel, diplomats confront the same historic suspicions.
An example of the delicacy of the bargaining emerged in Moscow this week when world powers, meeting as new EU sanctions loomed and fears grew of an Israeli strike against Iranian installations, succeeded only in agreeing on a followup meeting of experts. The date proposed by western nations was July 2.
An unfortunate error. According to the Persian calendar, that is the anniversary of the day in 1988 when a U.S. warship shot down a civilian Iranian airliner, killing all 290 mostly Iranian passengers and crew, including dozens of children.
"Needless to say this is a date of some deep feeling by the Iranians. Dr. Jalili reminded us of that. And we changed the date to July 3. It was a passing moment, and unfortunate," a senior U.S. administration official said, referring to chief Iranian negotiator Saeed Jalili. "But those things happen."
Other parts of the Iranian nuclear dispute have not been nearly so easy to resolve.
Washington has spearheaded the global diplomatic offensive to tighten sanctions on Iran which it believes is seeking nuclear weapons, a charge Tehran denies.
Behind closed doors, the talks between Iran and the so-called P5+1 group of powers - United States, Russia, China, Britain, Germany and France - tend to be polite and correct, reflecting little of the brittleness of their public statements.
Organisers strain for a conducive mood, especially important as the Iranians are so outnumbered by counterparts from the United States, Russia, China and European powers.
In Baghdad, delegates sat at a large round table felt to be less confrontational. In Moscow the teams sat at two separate rectangular tables opposite each other, with flowers in the middle. That was, according to one delegate, actually closer than they had been in Baghdad, making communication easier.
Cultural differences also play a role.
In the past, said U.S.-based Iran expert Trita Parsi, Iranian diplomats would coat their arguments in layers of historical and cultural context.
"The Iranians give these very lengthy opening statements. They want to convey a very abstract theoretical framework for Iran's foreign policy," Parsi, whose recent book 'A Single Roll of the Dice' examines U.S. diplomacy with Iran, told Reuters.
HISTORICAL LECTURES 'A KILLER'
They go into everything from the love of God, the importance of justice in Islam, to Persian poetry, and then they establish the principles of Iranian foreign policy," he said. "It exhausts the Westerners."
Such speeches, Parsi argues, had been an element of Iranian negotiating tactics that aimed at gaining an upper hand in talks and jarred sharply with the Western approach. "For the unprepared western diplomat, it is a killer," he said.
Conversely, a Western desire for efficiency and clarity in talks means the Iranians have often felt misunderstood in negotiations, aggravating mistrust between the two sides.
"When the U.S. moves too quickly and they get too quickly to the point, it kind of violates the Iranian rules about the amount of time that needs to be given to foreplay in negotiation," Parsi said.
Then there is history again.
British-American complicity in the overthrow of Iranian nationalist Prime Minister Mohammad Mossadeq in 1953 lives on in the collective memory of Iranians, as does Western support for Iraq in its 1980-88 war with Iran
"We behave as if peacemaking is a rational process, but ultimately it is highly influenced by the history and trauma of the conflict," Western academic Gabrielle Rifkind wrote in a 2011 study for the independent Oxford Research Group.
Bereft of mutual confidence, diplomats on both sides have struggled to find points of compromise. Though in the same building, the communication can be tortured.
Recent talks in Baghdad were a case in point.
At the venue in an Iraqi government guest house, two men walked into a delegation's rooms during the talks and started making photocopies. When asked what they were doing there, they said they thought they were at the venue's business centre.
When they walked out, two sheets of paper were left behind which described the Iranian negotiating stance on Syria and Bahrain - two hotspots Iran wants debated as part of the talks.
Diplomats at the meeting said there were two schools of thought to explain what happened. A mistake? Or a deliberate ploy to deliver a message?
Sometimes, there can be theatrics.
In 2003, Ali Akbar Salehi, then Iranian ambassador to the U.N. nuclear watchdog, the International Atomic Energy Agency (IAEA) and now Foreign Minister, went up to the U.S. ambassador to the IAEA at the time, Kenneth Brill, during an agency board session on Iran's nuclear programme. According to several members of the U.S. delegation at the time, he leant over and whispered into Brill's ear: "You're going to love this."
Salehi then marched up to the podium and launched into a tirade about the U.S. and IAEA secretariat and the pressure Tehran was under over its nuclear program.
He then declared that the Iranian delegation was leaving the meeting room, which they did. Outside the closed-door meeting, the Iranian delegation handed out Salehi's speech, replete with words in all caps and exclamation marks.
According to Western delegates, one hopeful sign in recent weeks was the disappearance of very long historical speeches at the start of meetings, notably at talks in Istanbul on April 14.
Jalili and Catherine Ashton, the European Union foreign policy chief who represents the six powers in dealings with Iran, shared a private dinner at the Iranian consulate in the Turkish capital the night before official meetings.
The mood was friendly and they swapped views on the Arab Spring and women's rights, and tales of their home towns.
Jalili, a 46-year-old politician sporting the rounded collar of Shi'ite clergy and no tie - these are often dismissed in Iran as symbols of western decadence - reminisced about the blue-tiled mosque in Mashhad, Iran's second largest city and one of the holiest places in Shia Islam.
The next day, the Iranian negotiator, who had been described by Western diplomats as "unbearable" in previous years, publicly said discussions had been positive. He seemed to follow a pre-agreed line, in stark contrast to previous occasions when he had sparred with Ashton.
WEST SEEKS "REGIME CHANGE"
Subsequent talks, however, have not proven easy.
Analysts say the Iranian leadership's overarching concern in its dealings with the West is that its foes ultimately want to overthrow the system of Islamic clerical rule, and the nuclear row is merely a means to that end.
"Iranians really doubt the ultimate goal of the Western powers on the nuclear issue, whether they are going to use the nuclear issue as an instrument to place sanctions, pressures ... to bring regime change in Iran," former Iranian negotiator Hossein Mousavian told Reuters.
It is likely to be a suspicion shared by Jalili, who lost a leg fighting in the 1980-88 Iran-Iraq war.
Western diplomats say they suspect it is his suffering in the war that helps make him a formidable negotiator with the West, seen by Tehran as Baghdad's ally during that conflict.
Mousavian conceded that Jalili was perhaps a little more suspicious towards the West than his predecessor (Ali Larijani) "because maybe ... his understanding about the West is very negative, especially about the U.S." But Jalili was only reflecting a general Iranian suspicion of America, he added.
For their part, Western nations question Iranian good faith by pointing out that Iran's enrichment takes place at plants that were built in secret and only made public by others.
Despite the history of tension between Iran and the West, there have been instances of U.S.-Iranian cooperation.
In the aftermath of the Sept 11 attacks, Washington joined with Russia, Iran, India and Afghanistan's Northern Alliance to topple the Taliban and later worked closely with Tehran on the Bonn conference that set up a successor government in Kabul.
James Dobbins, Washington's point man in those contacts, has positive memories of working with Tehran, and in 2007 testimony to Congress he urged Washington to speak to Iran unconditionally and comprehensively.
SENSE OF MUTUAL GRIEVANCE
"Twenty seven years of non-communication has embedded this sense of mutual grievance more deeply in the Iranian and American national psyches. It is thus unrealistic to expect that our differences can be overcome in a single comprehensive breakthrough. It is even more foolish to believe that non-communication can advance that process..." he said.
"We spoke to Stalin's Russia. We spoke to Mao's China. In both cases, greater mutual exposure changed their system, not ours."
At one time the Iran talks were friendlier, says Peter Jenkins, Britain's representative to the IAEA from 2001-06, now a partner in a negotiation consultancy, ADRgAmbassadors.
"The E3 political directors got to know them as human beings...We ate together on some occasions and mingled during breaks he said, referring to an EU trio of Germany, France and Britain then leading the talks.
He told Reuters the atmosphere in the talks cooled when President Mahmoud Ahmadinejad came to power in 2005. "The chemistry was awful, like dealing with a Soviet official in the worst days of the Cold War, with no give and take," he said.
These days, the teams eat separately - a reality that produce the occasional attempt at humour.
In Bagdhad, the Iranian side ran out of main course plates during lunch. An Iranian delegate came over to the area where the teams from the six powers were eating to get some of their plates, and was greeted with a quip that ran along the lines of "you can have them, in return for some movement on 20 percent".
The West is demanding Iran halt its production of Uranium with a purity of 20 percent, which it sees as too close to the level needed for nuclear weapons.
"It is important with the Iranians not to lose one's temper or show that one is upset," a leaked State Department cable quoted Geoffrey Adams, then UK ambassador to Iran, as advising U.S. officials in November 2007.
"Trading accusations allows the Iranian government to rely on a familiar script; far better is to ask unexpected questions that will take them off-script." Adams, now political director at the Foreign Office (Ministry), was quoted as saying.
Tomes have been written on the art of dealing with negotiations that drag on apparently fruitlessly, many of them drawing on wisdoms from Cold War arms talks.
Ultimately, of course, the conduct of delegates conforms to the mood in their capitals. But talks develop a culture of their own and diplomats can develop a sense the politicians only interfere.
Richard Dalton, Britain's ambassador to Iran from 2002 to 2006, criticised political leaders for signalling in advance to the media their broad positions ahead of talks.
"This is a bane of these talks," said Dalton. "There's a kind of arrogance that says if we signal our position in advance the other side will recognise how tough we are and adjust its position accordingly. No negotiation of any difficulty or complexity was ever concluded on that basis."
"Both sides ought to shut up." (Additional reporting by Lou Charbonneau in New York, Fredrik Dahl in Vienna, Andrew Quinn in Washington, Patrick Markey in Baghdad, Thomas Grove in Moscow, Marcus George in Dubai and Zahra Hosseinian in Zurich; editing by Ralph Boulton/Janet McBride)