NATO has accused Russia of "aggressive military posturing" following reports it has deployed anti-ship missiles in the Baltic Sea exclave of Kaliningrad.
In a statement to the Associated Press, NATO said the missile deployment near the alliance's borders "does not help to lower tensions or restore predictability to our relations."
The Kremlin has defended Russia’s military buildup, citing NATO's "expansion" toward the country's borders.
"NATO is indeed an aggressive bloc," Kremlin spokesman Dmitry Peskov said on November 22. "Russia certainly has every sovereign right to undertake necessary measures on the entire territory of the Russian Federation."
The comments come a day after a senior Russian lawmaker was quoted as saying Moscow would deploy the S-400 missile-defense system and nuclear-capable Iskander missiles in Kaliningrad.
Viktor Ozerov, chairman of the defense committee in the upper house of parliament, said in remarks reported by RIA news agency that Russia was forced to react to the planned U.S. missile shield in Eastern Europe.
The U.S. State Department said the deployment of the S-400 and Iskander systems in the Russian territory bordering NATO member-states Lithuania and Poland "is destabilizing to European security.”
Moscow had previously said it was sending Iskanders to Kaliningrad as part of routine drills.
Moscow's relations with NATO have plunged to levels of acrimony unseen since the end of the Cold War following Russia's military seizure of Ukraine's Crimean Peninsula in March 2014 and an ensuing war between Kyiv's forces and Russia-backed separatists.
Based on reporting by Reuters, TASS, and Interfax