Finland could submit its application for Nato membership within weeks, its Foreign Minister Pekka Haavisto has suggested.
The Russian invasion of Ukraine has encouraged states such as Finland and Sweden to consider membership amid security fears.
Russia warned Finland in February to stay out of Nato.
Sergey Belyayev, head of the Russian foreign ministry’s European department, repeated the threat last month, stating that there would be “serious military and political consequences” if they joined.
Finland, a European Union member state, shares a 1,300-km (810-mile) border with Russia.
Haavisto said Russia’s invasion had shown that it is willing to take military risks and can quickly mobilise more than 100,000 soldiers against a neighbouring country.
"There we come to a situation in which we may need cooperation," Haavisto said, alluding to Nato.
He added that Nato member countries have offered to help Finland by ensuring its security during an application process. They estimate it would take from four months to one year to approve the application, he added.
"There is an important Nato summit in Madrid in June. Of course Nato is wondering whether Finland and possibly Sweden will have submitted their membership applications before that," Haavisto said.
He said the government will next week give parliament a review on how Russia’s decision to attack Ukraine has altered Finland’s security policy.
But he added the government was prepared to quickly propose joining Nato if there was sufficient support from parliament.
It comes as the former Prime Minister of Finland Alexander Stubb said the Nordic nation could decide to join Nato as soon as May.
Mr Stubb, who headed Finland’s government in 2014 and 2015, said: “In the beginning of the war I said that Putin’s aggression will drive Finland and Sweden to apply for Nato membership.
“I said it was not a matter of days or weeks, but months. Time to revise: Finland will apply within weeks, latest May. Sweden to follow, or at the same time.”