"Plans to deploy Iskander-M missiles in the Kaliningrad district are disturbing and Poland has said so many times," its foreign ministry said in a statement.
Warsaw said it had received no official word from Moscow about the deployment, which a Russian defence ministry spokesman confirmed today.
"This is a matter for NATO and we can expect possible consultations and action (...) at the NATO and EU level," it added.
Relations with Russia have been frosty since Poland shed communism in 1989 and went on to join NATO a decade later.
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"It is clear that it is alarming news as it is one of the arguments changing balance of powers in our region," Latvia's Defence Minister Artis Pabriks said today, quoted by the Baltic News Service (BNS).
"It does not change the balance of power between NATO and Russia, but it changes balance of power in the region. It threatens several Baltic cities," he added.
He was echoed by Estonia and Lithuania whose defence ministers termed the move both "alarming" and "cause for concern".
The advanced version of the Russian missile has a range of 500 kilometres (310 miles) and could potentially be used to take out ground-based radar and interceptors of the new NATO shield.
The Kremlin warned in 2011 that it could station the short- and medium-range ballistic missiles along the European Union's eastern frontier in response to NATO's missile defence programme.
Both the United States and the Western military alliance have argued that the shield is not aimed at Russia but is designed to protect the West from potential threats from so-called "rogue states".
The Kremlin also believes the shield could in the future be expanded to a point that makes Russia's own vast nuclear arsenal ineffective.