Russia's defence ministry revealed on Monday that it has moved nuclear-capable Iskander missiles closer to Europe's borders in response to the US-led deployment of a disputed air defence shield.
Germany's Bild newspaper first reported over the weekend that Russia had placed the ballistic missiles in its Kaliningrad exclave near Poland over the past 12 months.
A top Russian defence official said in response to the report that several Iskander batteries had been stationed in Russia's Western Military District -- a region that includes the exclave and also borders the three Baltic states, members of the European Union.
He did not confirm that the missiles had been placed in Kaliningrad.
"Iskander operational-tactical missile systems have indeed been commissioned by the Western Military District's missile and artillery forces," Russian news agencies quoted defence ministry spokesman Igor Konashenkov as saying.
He added that Russia's deployment "does not violate any international treaties or agreements" and should therefore not be subject to protests from the West.
The Kremlin warned in 2011 that it may deploy short- and medium-range missiles along the EU's eastern frontier in response to NATO's deployment of a missile defence system.
Both the United States and NATO have long argued that the shield is not aimed against Russia but is designed to protect the West from potential threats from so-called "rogue states".
But Moscow fears the system -- whose components include both ground-based radar and missile-positioning satellites -- may one day be turned into an offensive weapon that targets Russia's soil.
The Kremlin also believes that the system may one day be expanded to a point that makes Russia's own vast nuclear arsenal ineffective.