As Russia appears to be stepping up its support for the Syrian dictator Bashar al-Assad, it is worth reconsidering what is at stake for Russia in the Middle Eastern country’s civil war.

Should Assad fall, he would likely be replaced by a Sunni-majority government that is supported by America’s Sunni allies in the petroleum-rich region, such as Jordan and Saudi Arabia. For Russia, it would mean the loss of its only real ally in the Middle East.

Since world powers reached an agreement with Iran in July that should stop the country from developing nuclear weapons, Russia has rushed in to repair its relations with the Shia state — which also supports Assad. But they are still a far cry from the deep ties between Russia and Syria that go back to the Cold War.

At the time of the Soviet Union, Russia’s spies collaborated closely with their counterparts in Damascus. Russia also erected a naval base at Tartus, the second largest city in the northwest of Syria that is the homeland of Assad’s Alawite tribe.

Although the facility is small, it is now Russia’s only naval station outside the former Soviet Union and it allows Russian warships to repair and replenish without traversing the Turkish Straits and going to Sevastopol.

Today, Russia sees Assad’s regime as a bulwark against violent Islamism (even though Assad enabled the rise of the self-declared Islamic State in order to discredit the opposition against him) and worries that his collapse could imperil friendly autocrats in Central Asia if not Russia’s own authority in the country’s Muslim provinces.

Syria is also a big buyer of Russian arms. From 2000 to 2010, Russia sold the Syrian government around $1.5 billion worth of weapons, according to Russia analyst Dmitri Trenin.

He has argued that while the Tartus station and arms trade are significant, the more crucial argument in favor of Russia’s support for Assad is its resistance to the violent and internationally-endorsed overthrow of dictators.

Dmitri Gorenburg, an expert on Russia’s military, has similarly argued that the country’s primary goal in Syria is to prevent the establishment of norms that would allow for international intervention in response to government repression of domestic protests or unrest.

When Western powers pushed for such an intervention in Libya four years ago, Russia acquiesced. It abstained from a United Nations Security Council vote that gave the other Arab states and NATO a mandate to protect Libya’s civilian population. In Russia’s view, they seized on that opportunity to engineer regime change in Tripoli. The bombing of government and military targets enabled Libya’s opposition to find and kill Muammar Gaddafi and displace his regime.

“The Russians felt they had been played for suckers on Libya,” Robert Gates, America’s defense secretary at the time, told The New York Times in hindsight. “They felt there had been a bait and switch. I said at the time we would pay hell ever getting them to cooperate in the future.”

Russia saw the intervention in Libya as the latest in a series of broken Western promises, going back to the end of the Cold War when it believed Germany and the United States had committed to not expanding NATO eastward.

A similar sense of betrayal informed Russia’s occupation and annexation of the Crimean Peninsula from Ukraine.

When mass protests against the Moscow-backed government in Kiev erupted in late 2013, Russia believed the West must be behind the demonstrations. Genuine popular uprisings do not happen in Russia, after all, where democracy is managed. Vladimir Putin’s regime did not appreciate Ukrainians’ yearning to be properly European rather than live in a buffer zone between East and West. It also feared that a successful transition to Western-style democracy and free markets in this former satellite state could serve as a dangerous example to Russians themselves. So it restarted the Cold War.

Just as it saw the West trying to steal Ukraine from it, Russia sees the Americans and their allies trying to overthrow Assad. It won’t stand by and let that happen.

If Assad must go or — perhaps more likely — Syria must be split up to end the war, Russia will make sure it is part of the process. It doesn’t need to fight on Assad’s side to make that happen. It simply needs to be there, on the ground in Syria, to prevent the other Arab states and the West ignoring it when the time comes to decide the fate of Assad and his country.