Finnish President says he had 'calm and cool' chat with Putin after the nation decided to break decades of neutrality by pursuing NATO membership

• Finnish President Sauli Niinistö said he had a cordial chat with Putin.
• Niinistö comments come as the world watches how Russia will respond to Finland's NATO bid.

Finnish President Sauli Niinistö said on Sunday that he had a primarily amicable chat with Russian President Vladimir Putin after Finland made clear that it would abandon decades of neutrality by moving forward with an application to join NATO.

"Actually, the surprise was that he took it so calmly," Niinistö told CNN's Dana Bash on "State of the Union" of his conversation with Putin on Saturday.

Niinistö stressed that he wasn't naive about Putin's personal reaction, pledging to "follow up" and stay aware of how Russia would respond to the possibility of having another border nation in NATO. If Finland were accepted, it would roughly double the size of Russia's land border with NATO.

Last week, Russia warned Finland The Russian Foreign Ministry said on Thursday that Moscow would be "forced to take retaliatory steps, both of a military-technical and other nature."

By Saturday, Russian energy supplier RAO Nordic Oy, had cut off energy supplies to Finland as the country announced its plans to apply for NATO membership in the next few days.

Niinistö said that Putin's decision to launch a large-scale war against Ukraine changed his country's calculus on NATO neutrality, a policy that the nation had followed since the formation of the North Atlantic Treaty Organization after WWII and throughout the Cold War.

"It showed that they are ready to attack an independent, neighboring country," Niinistö said.

Finland also took note that Putin moved so aggressively against NATO's possible expansion, Niinistö added. His nation could not simply accept a reality where Moscow had the power to direct Finland's own foreign policy.

"So far we had thought, OK, we are non-aligned of our will, but when they said that that meant that we didn't have any will left," Niinistö said.

Finland has yet to formally apply for membership, a move that is expected in the coming days. NATO does not have specific membership requirements, but rather the alliance has general political, economic, and military standards. NATO's current members have to unanimously support any aspiring nation's bid.