Russia sells nuclear technology and weapons to Iran, and regularly blocks resolutions condemning its regime at the UN Security Council. And yet the two don't always get on. So why does Moscow stay loyal to Tehran?
Russia and Iran are neighbors, divided only by the Caspian Sea. Today their relationship is shaped largely by pragmatism, but that wasn't always the case. The 1979 Islamic Revolution in Iran was driven by anti-Soviet, as much as by anti-American sentiment.
Revolutionary leader Ruhollah Khomeini once summed it up like this: "America is worse than Great Britain, Great Britain is worse than America, and the Soviet Union is worse than both of them. One is worse than the other, and they are all more revolting than each other!"
The turning-point in Russian-Iranian relations only came at the beginning of the 1990s, when the two countries worked together to settle the civil war in Tajikistan. "Since then Iran is seen as a rational partner in Russia, unlike in the West, with whom it is perfectly possible to find compromises," Fyodor Lukyanov, editor-in-chief of the journal Russia in Global Affairs, told DW.
"Moscow stays loyal to Iran, because the Iranians understand and respect Russia's security interests - particularly in Central Asia and the Caucasus," agrees Walter Posch, Iran expert at the Berlin-based German Institute for International and Security Affairs (SWP).
Important trading partners
In the past decade, Russia has risen to become one of Iran's leading trading partners. The trade volume has risen steadily in that time - from $1 billion to $3.8 billion (0.78 - 2.95 billion euros) between 2005 and 2008 alone. Russia mainly sells Iran nuclear technology, weapons, and wheat, while in return Iran exports food, oil products, and textiles.
Russia's most important energy project in Iran is the completion of a nuclear power station in Bushehr, whose construction began in the 1970s as an Iranian joint venture with German giant Siemens. In 2011 Bushehr became the first Iranian nuclear power plant to be connected to the national grid.
But very often the political cooperation between Moscow and Tehran is far from harmonious. "The two do not consciously share a strategic alliance, their common interests are limited," said Lukyanov. "Political relations between Russia and Tehran are complex and often marked by mutual accusations."
Nuclear ambitions and other bones of contention
The Iranian nuclear program is the main point of conflict between Iran and the West. Moscow has no interest in Iran developing a nuclear weapon either, says Posch, but at the same time it wants to stop any military action on Iran from the West. "At all costs, they want to prevent what happened to Iraq in 2003."
Meanwhile, the states bordering the Caspian Sea - including both Russia and Iran - have been bickering over the international status of its waters for years. The "new" countries among them - Azerbaijan, Kazakhstan, and Turkmenistan - want the sea to be redefined as "inland waters," which would give them additional extraction rights for the oil and natural gas there. But Iran and Russia both profit from the status quo - giving them a common interest. Moscow and Tehran also share worries about the situation in Afghanistan after 2014, when most of the western troops are due to withdraw. "An emergence of al Qaeda-like, Salafist, and radical Sunni groups in Afghanistan and the entire region is more of a worry for both states that Iran's nuclear program," said Posch.
Maintaining the status quo
On top of that, Moscow profits economically from the tensions between Iran and the West. The sanctions against Iran mean that an important competitor for Europe's lucrative energy market is isolated. On top of that, the reciprocal threats between the Iranian regime and the West help to drive oil prices up. A war could even mean a blockade of the Strait of Hormuz, a narrow passage of water through which up to 40 percent of the world's oil supply passes every day.
Posch sees many advantages for Russia in the current situation too. "Russia is a part of the so-called 5+1 group [including the UN veto nations Russia, the US, China, Britain, France, and Germany] when it comes to the Iranian nuclear program," he said. "The Iranians have problems selling their products in Europe. That's where Russia jumps in. The Kremlin is engaged in Iran's weapons industry." Moscow also profits from the fact that the West needs Russia's help for dialogue with Iran.
Sanctions limit Russia's engagement
But the West's sanctions against Iran are also a thorn in Russia's side, because they prevent Russia's deeper engagement with Iran. The Russian oil company Lukoil, for example, was forced to end its activities in Iran in 2007, when the US extended its sanctions to cover companies active in the country. That decision meant Russian companies had to decide whether they wanted to do business in the US or in Iran. Lukoil chose the former. In 2011, a subsidiary of Russia's gas giant Gazprom had to abandon plans to open an oil field in Iran for similar reasons.
And the UN sanctions also hamper Russian weapons exporters. In 2010 Russia was unable to deliver to Iran an S-300 ground-to-air missile system that it had already built -according to Russian sources, that particular disappointment left a several-hundred-million-euro hole in the Russian economy's pocket.