Russia will have to respond if Sweden and Finland become NATO members, Russian Foreign Ministry spokesperson Maria Zakharova said Friday.

"All OSCE member states in their national capacity, including Finland and Sweden, have reaffirmed the principle that the security of one country cannot be built at the expense of the security of others," Zakharova told a press briefing in Moscow.

"Obviously, the accession of Finland and Sweden to NATO, which is primarily a military alliance as you well understand, would have serious military and political consequences," subsequently requiring Russia to make response steps.

On Thursday, NATO Secretary-General Jens Stoltenberg invited Sweden and Finland to attend a NATO virtual summit on the situation in and around Ukraine on Friday. 

Finnish Prime Minister Sanna Marin, on the same day, said Finland would be ready to join NATO "if the issue of national security becomes acute."

Russian armed forces to ensure UN, OSCE security

The Russian armed forces will be taking measures to ensure the security of UN and Organization for Security and Co-operation in Europe (OSCE) personnel in Ukraine, spokeswoman Zakharova said.

"Russian soldiers will take all necessary measures to ensure the safety of the UN and OSCE missions' personnel in Ukraine," Zakharova told a briefing.

The whole dispute over Ukraine and the Russian-Western issue altogether is caused by NATO looking to admit Ukraine as a member of the alliance and Moscow opposing such accession due to security concerns.

Russia has for months been warning of the threat posed against it by NATO's attempts to expand eastward, which happened simultaneously with an increase in NATO military activity along Russia's borders, and batches of lethal weapons being sent to Ukraine, prompting Russia to request security guarantees from the West. Washington failed to provide the guarantees.

Vladimir Putin authorized a special military operation in Donbass over the constant Ukrainian shelling of Lugansk and Donetsk People's Republics, whose independence Moscow recognized a few days ahead of the operation.