Tensions remain high between the two countries over the unresolved status of Nagorno-Karabakh, a region that lies within Azerbaijan but has been under the control of Armenian troops and ethnic Armenian forces since a six-year separatist war ended in 1994.
Russia has long maintained S-300s on its base in Armenia, but Wednesday's announcement was the first acknowledgment that Armenia has missiles of its own. It is not clear how long Armenia has had them.
Defense Ministry spokesman David Karapetyan said the missiles would "coerce Azerbaijan into keeping the peace."
