Russia built Iran's first nuclear power plant, once sold Tehran sophisticated weaponry, and refuses to back further international sanctions over Iran's controversial nuclear program, but this apparent coziness belies years of suspicion and growing distance between the two nuclear powers.
Despite the fact that Russia is training hundreds of nuclear scientists to operate the Bushehr plant, Russian analysts say that Moscow has contributed little to Iran's recent strides in uranium enrichment and nuclear technology.
Iran has been locked for months in negotiations with world powers over limiting its nuclear program, as Israeli leaders have threatened to conduct military strikes against Iranian nuclear facilities. Russia straddles both camps, but has its own turbulent history with Iran that complicates its role.
Gone are the dangerous, free-wheeling 1990s, when the collapse of the Soviet Union left legions of nuclear and missile engineers without work and willing to sell their services to the highest bidder – with Iran reported to be a frequent destination.
And the ranks of Iranian students studying nuclear and other physical sciences in Russia was thinned out years ago due to official concerns about spying and the ultimate purpose of the Islamic Republic's expertise, Russian experts say.
Even at the height of their cooperation, Russia imposed limits on the collaboration.
"The Kremlin did not want Iran student specialists to come here, because they had the impression they were not just students, but fundamentalist Islamists," says Rajab Safarov, director of the Center for Studying Modern Iran in Moscow.
A senior Kremlin official once told him: "God save us! Why do we have these agents of Islamic radicalism here?" recalls Safarov. "Because once you have them, you don't know whom you are preparing, who is by your side."
One result has been that warm rhetoric about Iran-Russian ties – such as when President Vladimir Putin says Russia “has always defended the rights of the Iranian nation” – is more talk than reality.
"It is difficult to find another country whose relations with Moscow have experienced so many drastic twists in a such a relatively short time," writes Nikolay Kozhanov in a June analysis for The Washington Institute for Near East Policy.
Taking over for the US
Iran's nuclear ambitions predate the 1979 Islamic revolution. Back then, American companies were among those bidding to build 20 power reactors for the pro-West Shah Mohammad Reza Pahlavi.
"The media picture is not quite balanced," says Anton Khlopkov, director of the Center for Energy and Security Studies in Moscow, which is compiling a history of enrichment in Iran.
"I can tell you it was not Russia that launched this [Iran nuclear] project," says Khlopkov, editor of the Nuclear Club journal. "What is the driving force behind [Iran's] program today are the specialists trained in the US; hundreds went to MIT, Harvard, Berkeley.... If we want to understand the advance of Iran's programs, we must start in the 1950s and 1960s."
But the US ceased its support after the Islamic revolution, and the Soviet Union, too, was considered an enemy until its collapse.
Today, Russia has so far completed training for 524 Iranians to operate Bushehr, Iran's $1 billion, 1000-megawatt reactor on the Persian Gulf coast, as part of a contract signed in 1995. Its completion was delayed for more than a decade, and the reactor finally reached full capacity for the first time last week.
Another 160 Iranians have started training, while 14 are undergoing "in-depth" work, according to Eduard Saakov, general director of Atomtekhenergo, the branch of Russia's state nuclear energy corporation Rosatom.
Iranians trained here will be "directly responsible for safety of the nuclear power station," says Mr. Saakov. The Russian nuclear fuel Iran uses is under safeguard of the UN nuclear watchdog agency.
"Instructors who train Iranian experts are guided by requirements of the approved programs and procedures," says Saakov. "Training of Iranian personnel for any other programs but Bushehr is absolutely excluded."
Distrust erodes cooperation
Such limits today are in stark contrast to the 1990s, when Russia appeared to have a much more flexible policy toward Iran.
The Bulletin of the Atomic Scientists in 2001 quoted a mid-2000 CIA report: "Despite some examples of restraint, Russian businesses continue to be major suppliers of WMD equipment, materials, and technology to Iran," the CIA report read. "Specifically, Russia continues to provide Iran with nuclear technology that could be applied to Iran's weapons program."
Acting under US pressure, Moscow suspended several sensitive deals in the late 1990s. Israeli intelligence identified the then-head of the Russian atomic energy ministry (Minatom), Yevgeny Adamov, as the "mastermind behind the technology transfer to Iran," according to the Bulletin. He was described as an "oldstyle ideologue" resentful of his country's decline, who "needs to find work for his under-employed scientists and engineers as well as hard currency."
A Washington Post investigation in early 2002 confirmed what it called "the existence of an underground railroad of Russian scientists traveling to Iran to work on missile and nuclear weapons programs" in the 1990s. It quoted Vadim Vorobei, a Russian who first went to Iran in 1996 and was amazed by how many fellow former Soviet missile scientists he bumped into at hotels and restaurants.
"There was something artificial about it," recalled Mr. Vorobei, who was among the first experts to lecture in Tehran. "They were trying to show that a lot of Russians were working for them and everybody else should be scared by it."
But the Russian contribution was "limited by Iranian paranoia and secretiveness," the Post reported.
"They wanted to receive information from us, but at the same time they were not willing to tell us everything they were doing," said Vorobei. After lectures, students would pepper him with questions, and sometimes show him blueprints of a missile part, and ask if the designs were "in a good way or a bad way."
Iran began to be "disillusioned" with the Russians in 1998, about the time that Russian authorities – despite reports that Russian security officials took commissions from Iranian procurement agents – started to clamp down, noted the Post. The US cancelled $1 million in research contracts to Vorobei's Moscow Aviation Institute over the Iran ties.
Legacy lives on at Parchin military base
The legacy of the 1990s still reverberates today. A former Soviet nuclear scientist from Ukraine, Vyacheslav Danilenko, has been a key source for the UN International Atomic Energy Agency (IAEA) investigation into the sprawling Parchin military base southeast of Tehran.
Mr. Danilenko claims he was unaware of any nuclear weapons applications of his work in Iran from 1996 to 2002, when he was working as a specialist in creating nanodiamonds for industrial use.
But IAEA inspectors believe a large explosives containment vessel, built at Parchin in 2000 using Danilenko's expertise, may contain clues which the IAEA reported in November 2011 would be "strong indicators of possible [nuclear] weapon development."
Fresh access to the site – it was inspected twice before, in 2005, but not the buildings under new scrutiny – has yet to be granted by Iran.
Instead, the IAEA last week stated that satellite images of Parchin showed the site being sanitized by the Iranians, with "significant ground scraping and landscaping" that had "significantly hampered" the IAEA's ability to detect any past work with radioactive material.
Halting Iran's empire ambitions
Analysts agree that Russia has its own reasons to prevent Iran from ever going for a nuclear weapon – a step that Iran's supreme religious leader Ayatollah Ali Khamenei has rejected as un-Islamic and a "sin."
"Russia does not want Iran to have nukes, not because Iran is dangerous – they don't invade countries – but because of its own self-interest. They think that if Iran has nuclear weapons, it will change everything," says Lana Ravandi-Fedai, an Iranian researcher with the Institute of Oriental Studies at the Russian Academy of Sciences, referring to the region's balance of power.
"Everyone forgets about the national psychology of Iranians, it's a cocktail of empire feelings, of the Persian Empire," says Vladimir Sazhin, an Iran expert with the Institute of Oriental Studies. "The Islamic Republic of Iran must be the empire in the Middle East."
Mr. Sazhin says Iranians were excluded from studying natural sciences after some were "found to be spies" in the late 1990s.
"There were several cases when Iranian post-graduates tried to buy technologies here and tried to contact Russian experts working in national defense," says Yevgeny Novikov from the Russian Institute of Strategic Studies. "All Iranians who were excessively interested in Russian technologies and specialists were expelled."
That has been just one damaging episode in Russia's recent turbulent history with Iran.
"Moscow uses Iran as leverage in its political dialogue with Washington," which is of much greater importance to Russia, notes Mr. Kozhanov of the Washington Institute.
Russian distrust of Iran's nuclear intentions dates to the 2002 revelations about undeclared Iranian nuclear facilities, which "drastically affected Russian cooperation," says Kozhanov. Iran later also turned down a string of Russian enrichment proposals, "seriously irritating Russian authorities and provoking them to support" UN sanctions.
Weapons deals were cut back, and in 2010 one sale of great interest to Iran – of the S-300 air defense system, which Iran wanted to deploy around its nuclear facilities – was suspended.
None of that changes the advanced knowledge Iran already has, analysts say.
"They have a lot of experts, who are devoutly doing this work in the Islamic Republic," says Vladimir Sotnikov, a senior researcher at the Institute of Oriental Studies. "Iranians have enough expertise to continue for years with a nuclear weapons effort, if they want.... This remains in Iran."