Finland will seek to join NATO, leaders say, ditching decades of neutrality despite Russia’s threats of retaliation

(CNN) - Finland's government said Sunday it intends to join NATO, ditching decades of neutrality and ignoring Russian threats of possible retaliation as the Nordic country attempts to strengthen its security following the onset of the war in Ukraine.

Sweden's ruling party later said it will also support joining the alliance.

The decision was announced at a joint press conference by President Sauli Niinistö and Prime Minister Sanna Marin, who said the move must be ratified by the country's parliament before Finland can formally seek membership of the alliance.

"We hope that the parliament will confirm the decision to apply for NATO membership," Marin said in Helsinki on Sunday.

"During the coming days. It will be based on a strong mandate, with the President of the Republic.

We have been in close contact with governments of NATO member states and NATO itself."

"We are close partners to NATO but it is a historic decision that we will join NATO and hopefully we are making the decisions together," she added.

The move would bring the US-led military alliance up to Finland's 830-mile border with Russia, but could take months to finalize as the legislatures of all 30 current NATO members must approve new applicants.

It also risks provoking the ire of Russia, whose president, Vladimir Putin, told his Finnish counterpart Niinistö on Saturday that abandoning military neutrality and joining the bloc would be a "mistake," according to a Kremlin statement.

On Saturday, Russia cut its electricity supply to the Nordic country following problems in receiving payments.

Since the end of World War II, during which Finland was invaded by the Soviet Union, the country has been militarily non-aligned and nominally neutral in order to avoid provoking Russia.

It has indulged the Kremlin's security concerns at times and tried to maintain good trading relations.

The invasion of Ukraine has changed that calculation.

On Saturday, Niinistö called to inform Putin of Finland's intentions to join the bloc, saying "the Russian demands in late 2021 aiming at preventing countries from joining NATO and Russia's massive invasion of Ukraine in February 2022 have altered the security environment of Finland," according to a statement from the Finnish president's office.

Marin reiterated the sentiment on Sunday, telling reporters that in regards to a nuclear threat, "we wouldn't make these decisions that we are making now, if we didn't think that they are enhancing our strength or security.

So of course we believe these are the right decisions and they will enhance our national security."

Sweden has expressed similar frustrations, and on Sunday the ruling Social Democratic Party announced the country should work toward joining NATO.

A statement on the party's website said the party should, in case the application is granted by NATO, work to state unilateral conditions against the placement of nuclear weapons and permanent bases on Swedish territory.

Swedish Prime Minister Magdalena Andersson on Sunday called Russia's invasion of Ukraine "illegal and indefensible," adding that her country "can't rule out" that Russia would take the same action "in our immediate vicinity."

"And this is what Sweden now has to consider, and given this, we feel that Sweden needs the formal security guarantees that a NATO membership brings," Andersson said during a press conference.

Swedish Foreign Minister Ann Linde, meanwhile, called the move "a historic decision" in a tweet after the announcement, adding, "The Russian invasion of Ukraine has deteriorated the security situation for Sweden and Europe as a whole."

Both countries already meet many of the criteria for NATO membership, which include having a functioning democratic political system based on a market economy; treating minority populations fairly; committing to resolve conflicts peacefully; the ability and willingness to make a military contribution to NATO operations; and committing to democratic civil-military relations and institutions.