Russia has stated that it will be forced to take “retaliatory measures” in response to Finland’s decision to join NATO.
According to a statement from the foreign ministry, the decision would gravely harm bilateral relations as well as northern European security and stability.
Finland’s president and prime minister have previously urged the country to apply for Nato membership “as soon as possible.”
After Russia invaded Ukraine, public support for Nato membership skyrocketed.
Finland and Russia have a 1,300-kilometer (810-mile) border. To avoid antagonising its eastern neighbour, it has kept out of Nato until now.
After consideration by parliament and other key political officials, Finland will formally announce its choice on Sunday.
Sweden has stated that it will make a similar announcement on the same day.
Jens Stoltenberg, the Secretary-General of NATO, has stated that he expects Sweden and Finland to join “very rapidly.”
The White House stated that if both countries applied to join NATO, the US would support them.
A Russian statement (in Russian) termed Finland’s move “a major departure in the country’s foreign policy.”
Moscow, on the other hand, has not stated what steps it intends to take.
According to the Russian news agency Ria, Russia’s deputy UN representative, Dmitry Polyansky, indicated that if Sweden and Finland join Nato, they could become targets for Russia.
Russian officials were reacting to a joint statement by Finnish President Sauli Niinisto and Prime Minister Sanna Marin in which the two leaders said they expected a Nato membership decision in the coming days.
Last week, a poll found that 76 per cent of Finns support joining NATO, with only 12 per cent opposed, marking a significant shift toward participation since the invasion.
During World War II, Finland and the Soviet Union were on opposing sides, with the Finns famously repelling a Soviet invasion in 1939–40. However, Finland lost 10% of its land in the final peace accord and remained a non-aligned country during the Cold War.
If Russia joined Nato, its borders with the organisation would be more than doubled. Sweden and Russia do not share any borders.