Syria, rocked by an armed revolt against President Bashar al-Assad since March 2011, has close links with Russia, an ally since Soviet times from which it buys most of its weaponry.
The conflict, which started with peaceful protests as Arab Spring revolts rocked Tunisia and Egypt, soon escalated into a civil war in which more than 110,00 people have died, according to a rights group.
-- 2011 --
- April 27: Russia and China block a declaration submitted by Western countries at the UN condemning repression of peaceful protests by Assad's government.
- October 7: Russia's then president Dmitry Medvedev tells Assad either to reform or resign, while warning the West that Russia will fight outside attempts to oust him.
-- 2012 --
- January 8: A large Russian flotilla led by an aircraft carrier docks at Tartus, a port where Moscow leases a naval base from Damascus. In April, a top defence official tells the Ria Novosti news agency Russia will keep a permanent presence on the Syrian coast.
- June 30: World powers meeting in Geneva agree to a plan for a transition in Syria, before differences emerge over its interpretation.
- July 18: Russia and China veto for a third time in nine months a Western-proposed UN Security Council resolution that would threaten sanctions against Assad if he does not end the use of heavy weapons.
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- October 10: Ankara forces a Syrian passenger plane from Moscow to Damascus, reportedly carrying arms, to land in the Turkish capital.
- November 27: Russia only has a "working relationship" with Assad, Prime Minister Medvedev says, insisting that "privileged" ties were a thing of the past.
-- 2013 --
- January 27: In a rare attack on its ally, Russia accuses Assad of having made a "grave, perhaps fatal error" by delaying political reforms.
- March 13: Russian Foreign Minister Sergei Lavrov warns that any move to arm Syrian opposition forces would contravene international laws.
- August 21: Russia calls Syrian opposition claims of the Damascus regime launching a chemical weapons attack that killed more than 1,300 people a "premeditated provocation."
- August 27: Russia's foreign ministry warns a military intervention in Syria could have "catastrophic consequences" for the region. A Russian deputy prime minister says Western countries are behaving in the Islamic world like a "monkey with a grenade".
On September 2 it emerges that Russia has sent a reconnaissance vessel from its Black Sea fleet to the coast off Syria.
- September 4: President Vladimir Putin suggests Russia could approve military strikes against the Syrian regime if the West presents watertight evidence of chemical weapons crimes but warns the use of force without UN approval would be an "aggression".
He reveals that Russia has suspended deliveries of sophisticated S-300 missile systems to Syria.
Syria's deputy foreign minister, Faisal Muqdad, says Russia's position has not changed.