As Aeroflot Flight 515 from Moscow begins its predawn descent into Tehran, the group of middle-aged Russian experts on board begins to fill out landing cards for Iran.
Pulling out dog-eared, still-valid Soviet passports, the men write down their profession engineer and their destination: Bushehr, the city on the Persian Gulf that is home to Iran's nuclear-power project and to 1,000 Russian engineers and technicians.
Russia sees the Bushehr reactor as a mammoth civilian venture, an $800 million nuclear power project that adheres to international norms, brings home cash, and ensures close relations with the Islamic regime in Tehran.
But from the United States' perspective, oil- and gas-rich Iran doesn't need nuclear power. And so the reactor is an indication that Iran using the civilian project as a cover, the US alleges is gaining sensitive Russian technology that will help Tehran's hard-line mullahs acquire nuclear weapons and delivery systems. Curbing such proliferation is a key strategy of the US-declared "war on terror."
Despite top-level denials of wrongdoing from Moscow and Tehran, and piecemeal indications that Russia has refused several questionable Iranian requests in recent years, US officials say that illicit technology and know-how transfers from Russian entities to Iran are continuing, and could spoil rapidly warming US-Russia relations.
"The quality of the relationship with Russia really depends fundamentally on how they address this question in the future," John Bolton, the US undersecretary of state in charge of arms control, warned last week. Russia says it is playing by the rules, and that it has an even greater interest than the US in preventing nearby Tehran from acquiring nuclear capability.
Officially, the United Nations International Atomic Energy Agency (IAEA) says that both Russia and Iran for their declared nuclear projects are adhering to all guidelines. Russia notes that, under a nonproliferation agreement, the US is building a similar reactor in North Korea another country labeled by Washington as part of an "axis of evil."
But the secretive world of nuclear and missile exports; the murky role of Russia's security services, often vulnerable to bribery; and the desperation of Russia's nuclear scientists, impoverished since the USSR's fall, have created new risks. US concerns focus not on mishandling of nuclear materials at Bushehr which are to remain under internationally monitored Russian control but on the possibility that Russian know-how will create a nucleus of Iranian experts who could apply new knowledge to a weapons program.
"The new generation [of nuclear experts] may work in Iran, and may work on nuclear weapons, because their lives are too hard and they want money, money, money," says Valentin Tikhonov, a Russian Academy of Sciences expert who authored a report last year on the "human factor" of Russian proliferation, for the Carnegie Endowment for International Peace. "Most can't see the difference between working on civilian or war production for them it doesn't matter," Mr. Tikhonov says. "In these conditions it is difficult to speak about human values, about the dangers of their work. They only want to survive. It is a catastrophic situation." Most Russian nuclear scientists make less than $50 per month, according to the report.
Under US pressure, three key missile technology deals to Iran were stopped by Russian authorities in the late 1990s. And the sale of critical laser information that could help Iran make fuel for nuclear weapons was suspended in 2000. Still, US sources say such cooperation continues.
"[Russia] is giving meaningful help [to Iran] in mastering the nuclear-fuel cycle, and some critical technologies like sophisticated metal alloys [and for] laser isotope separation techniques ... that are involved in building the bomb," says a senior US official, who asked not to be further identified. "There's enough to see a pattern of a determined Iranian effort that has unfortunately struck positive responses from some Russian entities."
While Russia calls for evidence of US claims, however, passing on such intelligence is "tricky" because of Clinton-era cases that went awry, the US official says: "When some sensitive information was passed to the Russians, they didn't stop the activity, but they stopped the leak. That leads to great reticence to blow any more sources."
Russian analysts argue that Moscow's concerns about Iran precisely mirror Washington's, and that it also wants to stop "freelance" technology transfers.
"There is practically zero risk that Iran will use the Bushehr power plant for nuclear proliferation," says Vladimir Orlov, head of the PIR Center, a Moscow think tank, echoing some American analysts. He notes that Russia will cut Iran out of the nuclear-fuel cycle by supplying all such fuel itself and immediately taking spent fuel back to Russia.
"Russia doesn't want and will not support any ambitions of Iran which may be interpreted as nuclear weapons ambitions," Mr. Orlov says, adding that the US "exaggerates the situation."
Moscow has sometimes defied Iran's wishes, Orlov says. In the 1990s it refused Tehran's request to build a more robust heavy-water reactor. And Russia turned down a request for gas centrifuges, which could have led to production of homegrown- weapons-grade material.
Moscow's caution was illustrated earlier this year, Orlov says, when Iran asked to buy the Russian version of the shoulder- held US Stinger missile the Igla, or "needle" designed to shoot down aircraft. Angering Tehran, Russia said no because Iran's contacts with anti-Israel Hizbullah guerrillas in Lebanon meant Moscow was "not certain that Igla would stay in Iran."
Still, Moscow is a key factor in any Iranian nuclear aspirations. "Russian technology is unique to the Iranian program, because it is the only game in town," says Rose Gottemoeller, a former Deputy Undersecretary of Energy responsible for nonproliferation programs, who is now at the Carnegie Endowment in Washington. "Everyone else has cut off cooperation with Iran on nuclear technology, including the Chinese."
While US officials worry that Bushehr will create a nuclear knowledge base in Iran that could be applied to a weapons program, Ms. Gottemoeller says the real risk comes from a "handful" of "bottom feeders small Russian industrial or research institutions that are desperate, or they wouldn't be trying to take extreme measures, such as false invoices ... to mask their sales."
The majority of nuclear-related entities here have decided to "stay on the straight and narrow," Gottemoeller says. Recent leadership changes at the top of the Ministry of Atomic Energy are likely to tighten controls further.
Still, says Gottemoeller, "the Russian system being what it is, I'm sure there are others [desperate institutions] who could pop out of the mud at any time."
Keeping that from happening has been the aim of US pressure on Russia for a decade, since some analysts say that any new nuclear power in the Mideast would almost certainly spark other nuclear weapons programs, and cause global nonproliferation accords signed by both Russia and Iran to collapse. Already, the Bushehr project is subject to regular IAEA inspection.
Noting that until now Russian controls on sensitive technology have been "half-hearted and incomplete," Gary Samore, a special adviser to Clinton on nonproliferation who is now at the International Institute of Strategic Studies in London, says: "There may be a real opportunity now, post-Sept. 11, for the US and Russia to work out an agreement that would give the Russians a strong incentive to go all the way in enforcing what they say is their policy."
Mr. Samore says the US should recognize that the Bushehr project is too advanced to stop, and offer to "grandfather" the deal. Russia would receive a variety of incentives, Samore suggests, for explicitly limiting the Bushehr deal to power needs, handling all fuel supplies, and for insisting on public commitments from Iran to swear off fuel-cycle ambitions and comply with tougher IAEA "go anywhere" inspections. Samore says such a deal would test Iran's declarations of peaceful intentions, while relieving it of waste-disposal problems. Tehran's rejection of such a plan would lead to the "obvious conclusion" about Iran's nuclear plans, he adds.
"The sooner you can step in to slow down or stop [Iran's] program, the better," says Samore. "If we just let the situation drift and don't do anything, they will get closer and closer, and will eventually reach the technical point of no return."
As the Bushehr project continues, Russian law enforcement will be critical in guarding against dangerous transfers of technology, experts say. "If their security is as effective as they claim it to be, and we think it is, they should be able to track these things down," says the US official who requested anonymity. "They know who is flying on Aeroflot to Tehran."