According to the Russian Foreign Ministry, the decision to deploy S-300 anti-air missile system in Syria came after receiving leaked data on US intentions to bomb Syrian airbases.
"The S-300 appeared there [in Syria] after experts close to the American establishment had started leaking information…that the US could hit Syrian airfields with cruise missiles," Foreign Ministry spokesperson Maria Zakharova said in an interview with Russia's Dozhd TV chennel.
The Russian Defense Ministry said on Tuesday that a battery of S-300 air defense systems had been delivered to Syria to protect the naval base at Tartus, as well as Russia warships deployed off the Syrian coast.
Earlier, Zakharova critized US Secretary of State John Kerry's statements on launching an investigation into "war crimes of the Russian Federation."