Finland's president and prime minister said on Thursday they were in favour of joining NATO and a formal decision would be taken this weekend, after Russia's war in Ukraine sparked a swift u-turn in opinion.
"Finland must apply for NATO membership without delay," President Sauli Niinisto and Prime Minister Sanna Marin said in a joint statement.
Niinisto has often served as a mediator between Russia and the West.
"NATO membership would strengthen Finland's security. As a member of NATO, Finland would strengthen the entire defence alliance," the statement said.
A special committee will announce Finland's formal decision on a membership bid on Sunday, the statement added.
The two leaders had been widely expected to come out in favour of joining the Western military alliance.
"Joining NATO would not be against anyone," Niinisto told reporters on Wednesday, amid Russian warnings of consequences if Helsinki were to seek membership.
His response to Russia would be: "You caused this. Look in the mirror," he said.
As recently as January, amid tensions between the West and Russia, Marin said a bid would be "very unlikely" during her current mandate, which ends in April 2023.
But after its powerful eastern neighbour invaded Ukraine on February 24, Finland's political and public opinion swung dramatically in favour of membership as a deterrent against Russian aggression.
A poll published on Monday by public broadcaster Yle showed that a record 76 percent of Finns now support joining the alliance, up from the steady 20-30 percent registered in recent years.
Finland shares a 1,300-kilometre (800-mile) border with Russia and has been militarily non-aligned for decades.
In 1939, it was invaded by the Soviet Union.
Finns put up a fierce fight during the Winter War but were ultimately forced to cede a huge stretch of its eastern Karelia province in a peace treaty with Moscow.
Iro Sarkka, a NATO expert from the University of Helsinki, told AFP before the announcement that Niinisto, who had refrained from revealing his stance on membership, had nonetheless dropped hints that he was leaning toward supporting a bid.
"The president no longer talks about the EU defence option or the role of Finland as the mediator between the East and the West," she said.
- Next steps -
On Wednesday, the Finnish parliament's defence committee also concluded that membership of NATO would be the "best option" for Finland's security, as the Russian invasion had eroded the security situation in Europe.
A large majority in Finland's parliament backs membership.
"It is 100-percent certain that Finland will apply and quite likely that it will be a member by the end of the year," researcher Charly Salonius-Pasternak of the Finnish Institute of International Affairs told AFP before Thursday's announcement.
Neighbouring Sweden is also contemplating joining the military alliance and the two countries are widely expected to present a joint bid.
For Finland, the next step is for the President and Ministerial Committee on Foreign and Security Policy -- a body made up of the president, prime minister and up to six other cabinet ministers -- to meet on Sunday.
The committee will make the formal decision for Finland to submit an application, with the proposal then presented to parliament.
After an official bid is submitted to the alliance, lawmakers in all 30 NATO member states would need to ratify its application, a process that can take months.
Foreign Minister Pekka Haavisto said on Tuesday he believed Finland could be a full NATO member "at the earliest" on October 1.
"The NATO secretary general has said that this process will take between four and 12 months. My own impression is that it might be closer to four months than 12 months," Haavisto said.