Russia's Defense Ministry has said the deployment of short-range missiles in the western part of the country does not violate any international agreements.
The ministry statement came in response to a report in the German daily "Bild" that said the missiles were deployed in Russia's westernmost Kaliningrad exclave wedged between NATO members Poland and Lithuania.
Ministry spokesman Igor Konashenkov did not specify where exactly the Iskander missiles are stationed.
The advanced version of the nuclear-capable Iskander missiles has a range of 500 kilometers.
Russia has long threatened to deploy the missiles in the Kaliningrad region as a countermeasure to a planned U.S. missile-defense system.
The Polish Foreign Ministry, as well as the defense ministers of Lithuania, Latvia, and Estonia voiced alarm over the reported deployment.
The U.S. State Department also expressed concern over the report.
Spokeswoman Marie Harf said Washington had urged Moscow not to destabilize the region.
In a related development, Defense Secretary Chuck Hagel told his Russian counterpart Sergei Shoigu on December 16 that a preliminary nuclear deal with Iran "does not eliminate the need" for the shield.
According to the Pentagon, Hagel stressed the plannes shield poses no threat to Russia.
Russian Foreign Minister Sergei Lavrov has argued the a deal with Tehran to curb its nuclear program would make the NATO shield unnecessary.
Based on reporting by AP and ITAR-TASS