MOSCOW (Reuters) - The Russian Defence Ministry said on Tuesday it had deployed an S-300 missile system to its Tartus naval base in Syria.

“The missile battery is intended to ensure the safety of the naval base ... It is unclear why the deployment of the S-300 caused such alarm among our Western partners,” the ministry said in a statement.

U.S. media reported earlier this week that Russia had sent the S-300 system to Syria at the weekend in its first foreign deployment of the surface-to-air weapon in the civil war-ridden country.

(Amends third para to make clear it is first S-300 system in Syria.)