Poland's defense minister, Tomasz Siemoniak, called out Russia for its "unprecedented" naval and air force presence in the Baltic Sea area this week. Siemoniak told reporters that although Russia was not preparing to attack, its military tests in the international airspace did "not serve to build good relationships and trust," BBC News reported.

Russia said it was only testing the NATO defenses that police the region, but tensions were high. NATO has previously alleged that Russia is giving its rebels in Ukraine weapons, and NATO previously reported it had seen a Cold War-level of intercepts since the start of the conflict in February.

NATO spokeswoman Oana Lungescu told Agence France-Presse that NATO's recent interception of six Russian bomber planes "represented a significant level of activity." Among the planes were four Tu-95 Bear strategic bombers, two Tu-22M Backfire long-range bombers, two Su-27s, Tu-134s and an An-72 transporter.

Russia occasionally does not provide flight plans for its warplanes, which could impact commercial airline activity. “Such activity can be destabilizing and potentially dangerous, if international norms are not respected,” Lungescu said.

Most of the Russian activity was in international waters and airspace, Siemoniak said. Sweden was most affected by Russia's increased military presence, BBC reported, but the Finnish air force also called the activity "unusually intense." Earlier this week, when Estonia claimed one of Russia's planes violated its airspace, the Russian defense ministry said it was just a routine flight.

In the meantime, Siemoniak urged Poland's residents not to panic over Russia's Baltic Sea presence but to be on guard. He said he planned to bring up the activity at a meeting with the defense ministers in Estonia, Latvia and Lithuania. 

“We know that the Russians say that their activity is a reaction to NATO actions,” Siemoniak said. “For us, this raises an alarm.”