Part of a series of articles looking at the regional interests at stake in Syria's civil war. The full list is on the left of your screen.
Syria has been a client state of Moscow's for over 40 years, and it is Russia's most reliable and last remaining partner in the Arab world. On those grounds alone, Moscow was bound to view Bashar al-Assad as Syria's rightful leader, and the rebellion that arose against him just over two years ago as illegitimate.
However, Moscow has a wide spectrum of reasons for supporting Mr. Assad and strongly opposing any outside intervention to remove him, beyond just protecting an established ally and arms customer.
As a country with its own bitter experience of revolution, dashed hopes and decades of suffering, Russia today is a deeply conservative society that takes a dim view of revolutionary enthusiasms wherever they break out.
Vladimir Putin, whose own democratic credentials are less-than-pristine, has argued successfully – to his own people at least – that the Arab Spring uprisings would not enlarge freedom, but rather would only produce chaos and empower extremists. So far, especially in Syria, he looks more right than wrong.
As a former superpower, keenly aware of how its own might has been diminished, Russia is suspicious and fearful whenever the United States brings its vast military superiority into play and sees self-interested geopolitical agendas lurking behind Western talk of "humanitarian intervention."
Hence, the Kremlin has dug in its heels and vetoed three UN Security Council resolutions that sought to license outside influence to ease Assad from power. Mr. Putin has repeatedly stressed that any military action taken without UN approval would be an illegal "act of aggression."
"From the outset, Russia has advocated peaceful dialogue enabling Syrians to develop a compromise plan for their own future," Putin insisted in an op-ed in The New York Times Wednesday.
"We are not protecting the Syrian government, but international law. We need to use the UN Security Council and believe that preserving law and order in today’s complex and turbulent world is one of the few ways to keep international relations from sliding into chaos," he added.
The Kremlin has warned of "catastrophic consequences" for Syria and the Middle East if the US intervenes unilaterally.
Russia has repeatedly said that it's not wedded to Assad, but wants to see a peace process in which the regime and rebels negotiate a "transition" between them. It would prefer some version of the present regime to survive, Russia-friendly and secular, if not necessarily democratic.
One important aspect of Russian policy, which receives very little attention, is that the powerful Russian Orthodox Church regards itself as the protector of Syria's Christians. The Kremlin listens to the Church, and at least some of its support for Assad is predicated upon preserving a government that protects minorities.
Moscow's worst-case scenario for Syria, frequently invoked in apocalyptic terms, would be the collapse of central government and the triumph of militant Islamists, who might spread instability and conflict around the region and into Russia's own nearby northern Caucasus.
But the Kremlin is also thinking globally. It aims to block US interventions, which it sees as neo-imperialistic and inimical to Russian interests. Russia has lost several client states due to what it views as Western meddling, from the former Yugoslavia, to Saddam Hussein's Iraq to Muammar Qaddafi's Libya in the past decade or so, and does not want to lose its last, Syria.
But unlike the former USSR, Russia would be willing to have a cooperative relationship with the US, and could see a joint US-Russian diplomatic solution for Syria – as long as it does not completely sweep away the existing regime – as the best possible outcome.