Finland formally declared its intent to join NATO Sunday as the historically neutral nation seeks to bolster its security amid Russia’s ongoing incursion into Ukraine.

The nation of roughly 5 million people shares a long border with Russia and the move is likely to escalate already searing regional tensions.

President Sauli Niinisto and Prime Minister Sanna Marin said they would pursue membership in NATO and that the Finnish parliament would vote on the matter in the coming days.

“This is a historic day,” Niinisto said. “A new era begins.”

Niinisto said he had a phone conversation with Russian President Vladimir Putin and said he took the news in stride.

In addition to Finland, Sweden and Georgia have also expressed a desire to attach themselves to the western military bloc as a buffer against Russian aggression.

Meanwhile, NATO leaders contended that the Russian offensive into Ukraine is withering and that a Ukrainian triumph is possible — especially with heightened external assistance.

“The brutal invasion by Russia is losing momentum,” NATO Deputy Secretary General Mircea Geoana said Sunday. “We know that with the bravery of the Ukrainian people and army, and with our help, Ukraine can win this war.”

Finland has been independent since 1917 and entered neutral status after a 1948 treaty with the Soviet Union.

The Nordic nation has a more than 800-mile border with Russia.