Russia says it will go ahead with deliveries of anti-aircraft missiles to Syria and that the arms will help deter foreign intervention.
Deputy Foreign Minister Sergei Ryabkov said the missiles were a stabilising factor that could dissuade "some hotheads" from entering the conflict.
He said the contract for the S-300 missile systems had been signed several years ago.
The S-300 is a highly capable surface-to-air missile system that, as well as targeting aircraft, also has the capacity to engage ballistic missiles, the BBC reports
Russia also criticised an EU decision not to renew an arms embargo on Syria.
European Union governments on Monday failed to renew the embargo due to differences in opinion.
However, in a declaration announced after 12 hours of talks, it agreed not to "proceed at this stage with the delivery" of equipment. The EU's Foreign Affairs Council is to review this position before 1 August.
Britain and France said they did not regard the August date as preventing earlier arming of Syrian rebels, but both countries stressed they had no plans to do so yet.
British Foreign Secretary William Hague said saying Britain isn't excluded from acting before August, but that it would not act alone if it chose to do so.
French Foreign Ministry spokesman Philippe Lalliot said Paris also reserved the right to send arms immediately to Syrian rebels but had no plans to do so.
He said France hoped there would be a breakthrough in finding a political solution over the next two months, but that the EU decision was a political declaration with no legal basis.
