Finland’s President Sauli Niinisto and Prime Minister Sanna Marin said Thursday that the country should apply to join NATO “without delay.”

Thursday’s announcement is the strongest sign yet that Finland will make a formal application to join NATO. Membership would be historic for the Nordic country, which has had a decades-long policy of military neutrality.

“Finland must apply for NATO membership without delay.” the leaders said in a joint statement, adding that they hoped that “the national steps still needed to make this decision will be taken rapidly within the next few days.”

“NATO membership would strengthen Finland’s security” and that Finland’s membership would in turn “strengthen the entire defence alliance.”

The government will debate the issue over the weekend and the Finnish parliament is expected to give its final approval to the application as early as Monday.

President Navasto said Russia’s invasion of Ukraine had changed Finland’s security situation although there was no immediate threat.

Soon after Finland’s announcement, fellow Nordic country Denmark said it would push for the quick NATO admission of Finland.

“Denmark will do everything for a quick admission process after the formal application,” Prime Minister Mette Frederiksen said on Twitter.

There is a risk the move from Helsinki could spark aggression from Russia, where President Vladimir Putin has expressed his opposition against NATO’s enlargement.

Finland shares a 830-mile border with Russia; if it joins the military alliance, the land border that Russia shares with NATO territories would roughly double (Russia has land borders with 14 countries and five of them are NATO members: Latvia, Estonia, Lithuania, Poland and Norway).

Finland has been reviewing its security policy in the wake of Russia’s invasion of Ukraine, which showed the Kremlin is willing attack a neighboring nation. Finland has been invaded in the past — in 1939, the Soviet Union attacked Finland in what became known as the Winter War.

NATO — or the North Atlantic Treaty Organization — was founded in 1949 by the U.S., Canada, and several Western European nations to provide collective security against modern Russia’s forebear, the Soviet Union.

Ever since its foundation, the alliance has had a thorny relationship with the Soviet Union throughout the Cold War, and following its collapse in 1991, the Russian Federation.

This is a breaking news story and will be updated shortly.