ALI MOORE, PRESENTER: The Syrian regime is estimated by the UN to have killed 2,500 of its own people during the past six months of protests, but president Bashar al-Assad is unlikely to face the same UN-endorsed military action or the level of sanctions that helped rid Libya of its dictator, Moamar Gaddafi.

For that, Assad can thank Russia.

According to Russian correspondent Norman Hermant, the Arab Spring has cost Moscow crucial Middle East allies and it's determined to hold on to its influence in Syria.

NORMAN HERMANT, REPORTER: The crowds in the street are still protesting and Russia's flag, along with China's, is being burned for its stubborn support of Syria's regime - despite a government crackdown that has killed thousands.

But Russia's president says Moscow has no plans to back sanctions against Syria - a longtime Middle East ally.

"We must not idealise this situation," says Dmitry Medvedev, "we must approach it from a balance of strongest interest". Russia's interest in Syria has everything to do with arms.

It hopes to sell Damascus new fighter jets, missile systems and artillery - in all, about $4 billion worth of contracts. Moscow is not about to lose another Mid-East customer, says this analyst, without a fight.

RUSLAN PUKHOV, ARMAMENTS INDUSTRY ANALYST: All other countries, they are not our kind of clients - they are clients of the United States, France, Britain. And if Syria also will follow, we will lose almost all our clients in the Middle East.

NORMAN HERMANT: The Arab Spring has not been good to Russia. Its ties to Moamar Gaddafi go back decades, and Moscow only reluctantly recognised Libya's new government. It was the 73rd country to do so.

That may put billions of dollars of construction and oil contracts at risk. Now many say the same scenario is playing out in Syria, where Russia has billions invested and a major naval base.

IRINA ZVYAGILSKAYA, INSTITUTE OF ORIENTAL STUDIES: Russia has a lot to lose in Syria. That is why Russia wants to find out less destabilising way out of the situation.

NORMAN HERMANT: More than anything, the Kremlin wants to be seen as standing by Syria. Russia has already halted missile sales to Iran, and it failed to veto UN Security Council action in Libya.

Many fear when it comes to repairing Russia's reputation as a reliable arms supplier, the damage is already done.