President Vladimir Putin stated Tuesday that the accession of Sweden and Finland to NATO would not pose a threat to Russia, but warned that Moscow would respond if the U.S.-led alliance reinforced military facilities in the new Nordic nations.

Putin, the supreme leader of Russia since 1999, has repeatedly attributed the post-Soviet expansion of the NATO alliance eastwards into Russia's borders as the cause of the Ukraine crisis.

But Putin, who in recent months has been saber-rattling Russia's nuclear capability at the West over Ukraine, responded with an out of character calmness to Finland and Sweden's applications to join NATO, the most significant geopolitical consequence of Russia's invasion of Ukraine to date.

"Regarding expansion, Russia has zero issues with these states. Therefore, there is no imminent threat to Russia posed by the extension of NATO to include these nations," Putin told leaders of a former Soviet military alliance headed by Russia.

Putin stated that the extension of military infrastructure into this territory would provoke our response.

Putin warned the heads of the Collective Security Treaty Organization (CSTO), which comprises Armenia, Belarus, Kazakhstan, Kyrgyzstan, and Tajikistan, "We will see what risks are manufactured for us."

The Kremlin chief's unusually calm response to one of Russia's most sensitive geopolitical concerns, the post-Soviet expansion of NATO, contrasted with his foreign ministry and top allies' stronger words.

Before Putin spoke, Russian Deputy Foreign Minister Sergei Ryabkov stated that the West should not assume that Moscow would simply accept the extension of NATO into the Nordic region.

Former President Dmitry Medvedev, one of Putin's closest allies, stated last month that if Finland and Sweden joined NATO, Russia may place nuclear weapons and hypersonic missiles in the Russian exclave of Kaliningrad. 

Putin delivered a brief address at the Grand Kremlin Palace in which he discussed NATO and criticized the United States for establishing biological laboratories in the former Soviet Union.

Putin stated that Russia had proof that the United States attempted to produce biological weapons components in Ukraine, an allegation both Washington and Kyiv have disputed.

In addition to NATO's "endless expansion agenda," Putin stated that the alliance was expanding well beyond its Euro-Atlantic scope, a trend that Russia was closely observing.

Moscow asserts that NATO poses a threat to Russia and that Washington has consistently disregarded the Kremlin's concerns regarding the security of its western frontiers.