Polish Defense Minister Tomasz Siemoniak has said Russia's military is engaging in an unprecedented amount of activity around the Baltic Sea.
"Over the past few days we have seen unprecedented activity by the Russians in the Baltic Sea, both the Baltic fleet and Russian aircraft," Siemoniak told Polish broadcaster TVN24.
The minister said that Poland, a member of NATO, was not under threat of attack and the Russian maneuvers were most likely designed to test how NATO forces in the region reacted.
Siemoniak said Warsaw's decision to acquire long-range missiles from the United States was due on the current tensions in the region.
The $250-million deal includes 40 joint air-to-surface missiles that are to be integrated into the Polish Air Force's three tactical squadrons of F-16 fighter jets.
Quoted by the AFP news agency, a NATO spokesman said more than 30 Russian aircraft had been intercepted in international airspace "over the Baltic Sea and off the coast of Norway," on December 8.
Last month, NATO reported that there have been around 400 intercepts of Russian military aircraft near NATO countries this year.
According to AFP, Lithuania put its military on higher alert on December 8 after 22 Russian warships were detected in the Baltic Sea.
Lithuania and the other Baltic nations of Estonia and Latvia have been on edge since Russia illegally annexed Ukraine's Crimea region back in March.
A report issued in November said the number and gravity of "close military encounters" between Russia and the West has increased visibly amid tension over Ukraine.
The report by the European Leadership Network detailed almost 40 dangerous or sensitive incidents over the past eight months, including what it says was the near-collision of a Russian spy plane and an SAS jet carrying 132 passengers from Copenhagen to Rome on March 3.
It says the incidents "add up to a highly disturbing picture" of airspace violations and other dangerous actions "over a very wide geographical area" from the Baltic and Black Seas to the U.S. and Canadian borders.