Russia has reportedly deployed ballistic missiles to the westernmost Baltic region, amid increasing tensions between the country and the west.
The S-400 air missile defence system and Iskander missiles were installed in Kaliningrad exclave, bordering Poland and Lithuania, to counter the potential threat from US cruise missiles.
US State Department spokesman John Kirby was quoted by Reuters as saying that the deployment of the missiles was 'destabilising to European security'.
Developed to replace the decommissioned OTR-23 Oka (Nato: SS-23) missile system, the Iskander mobile missile system engages ground targets, such as command posts and communications nodes, troops in concentration areas, air and missile defence facilities, and fixed and rotary-wing aircraft at airfields.
The S-400 Triumph air defence missile system engages aerial targets, including aircraft, unmanned aerial vehicles (UAV), and ballistic and cruise missiles within a 400km range.
Kirby was quoted by Reuters as saying: "Russia has made threats to move its Iskander missiles to Kaliningrad for the past decade in response to a variety of developments in Europe, none of which demand such a military response.
"We call on Russia to refrain from words or deeds that are inconsistent with the goal of promoting security and stability.”
According to the Interfax news agency, Russia has also set up Bastion missile launchers in the Kaliningrad exclave.
The Bastion fires supersonic Oniks cruise missiles, which are capable of engaging ship and ground targets within a 450km range.
Image: Russian Iskander missiles on the 9P78-1 Transporter erector launcher. Photo: courtesy of A.Savin.