WASHINGTON, Oct. 4 (UPI) -- The Russian government has put a new missile defense system into Syria, officials said Tuesday.
U.S. and Russian officials acknowledged the move, which sent a S-300 air defense system at a Russian military base in the port of Tartus.
Moscow's defense ministry, though, said the new defense system is merely a preventative measure.
"Let me remind you that the S-300 is a purely defensive system and poses no threat to anyone," defense spokesman Igor Konashenkov said.
U.S. officials became mildly alarmed at the news Tuesday, particularly in light of the fact that peace negotiations between Washington and Moscow have broken off.
"It is unclear why the deployment of the S-300 caused such alarm among our Western partners," Konashenkov said.
The S-300, also known as the SA-23 missile defense system, involves surface-to-air missiles to deter and combat an attack from the skies.
The shipment to Syria is the first time the S-300 has been deployed outside of Russia, officials said.
Moscow is aligned with Syrian President Bashar Assad's regime, which is engaged in a civil war with various rebel groups, who have received support from the United States.
Last month, U.S. and Russian officials reached a cease-fire agreement. It was called off, however, after less than a week. Monday, Washington said it is no longer holding peace discussions with Moscow to bring peace to Syria.