"Do you think we will continue to act in the same manner [if Finland joins NATO]?" visiting Russian President Vladimir Putin asked at a joint press conference with his Finnish counterpart Sauli Niinisto at the latter's summer residence in southwestern Finland on Friday.

"We have withdrawn our troops 1,500 [kilometers (932 miles) from the border]. Do you think they will stay there?" Putin said.

Back in April, Russian Foreign Minister Sergei Lavrov had likewise said that Russia would take appropriate military-technical measures at its northern borders if Finland's neighbor Sweden decided to join NATO.

Already reeling from mutual distrust, relations between Russia and NATO specially soured after the Black Sea Crimea Peninsula rejoined the Russian Federation from Ukraine following a referendum in March 2014.