Russian President Vladimir Putin warned the West on Monday that Russia would respond if NATO began to bolster the military infrastructure of Sweden and Finland, which have both decided to join the North Atlantic Treaty Organization (NATO).

Speaking at a summit marking Collective Security Treaty Organization's (CSTO) 30th anniversary in Moscow, Putin said Russia had no problem with Finland or Sweden, so there was no direct threat from NATO's enlargement, including those countries.

"But the expansion of military infrastructure into this territory would certainly provoke our response," Putin told the leaders of the organization, which includes Belarus, Armenia, Kazakhstan, Kyrgyzstan and Tajikistan.

"What that (response) will be - we will see what threats are created for us," said Putin. "Problems are being created for no reason at all. We shall react accordingly."

The meeting was also attended by Prime Minister of Armenia Nikol Pashinyan, President of Belarus Alexander Lukashenko, President of Kazakhstan Kassym-Jomart Tokayev, President of Kyrgyzstan Sadyr Japarov and President of Tajikistan Emomali Rahmon.

Lukashenko urged CSTO members to stand united and accused the West of hoping to prolong the conflict in Ukraine to try to weaken Russia as much as possible.

The Belarusian president noted that "hellish sanctions" against his country and Russia could have been avoided if the group had spoken with one voice.

"Stronger political cooperation and coordination by the CSTO member-states. The effectiveness of the mechanism of foreign policy and security consultations must be increased. We should speak out on behalf of the CSTO on international platforms more often to make the organization’s voice and stance well-heard and seen. There must be a common voice and a common stance, the way they are in the West," he said.

"Without a united front, the collective West will build up pressure on the post-Soviet space," Lukashenko added.

Heads of the Collective Security Treaty member states Monday also signed a statement of the Collective Security Council in honor of the 30th anniversary of the treaty and the 20th anniversary of the organization.

(With input from Reuters)