Putin warned that Russia would respond in kind if either country played host to the alliance's military forces.

Putin commented on NATO's formal invitation to the two countries while speaking to Russian state media.

We don't have the same problems with Sweden and Finns. They want to join NATO, according to Putin.

If military contingents and infrastructure are deployed there, we will have to respond in kind and create the same threats for the territories from which threats towards us are created, he said.

Russia's relationship with both countries would be subject to some new Tensions if they joined the alliance, according to Putin.

Putin said that everything was fine between them, but now there might be some tension. If there is a threat to us, it is inevitable.

After warnings from the Russians, Finn and Sweden joined NATO. Russia threatened to restore military balance in the Baltic regions if it was forced to do so.

Turkey agreed to allow the membership process to proceed after the two Nordic countries made bids.