This breakthrough came during a NATO summit in Madrid that has already become one of the most consistent meetings in the history of the military alliance.
The two countries are now expected to become full members of NATO quickly, propping up the bloc’s eastern flank just months after Russia’s invasion of Ukraine.
Here’s everything you need to know about why the move happened, what comes next, and why it’s important.
What’s the latest news?
Sweden and Finland announced their intention to join NATO in May, after Russia’s invasion of Ukraine led to a sudden change in attitudes to join the bloc.
That announcement was welcomed by almost all NATO leaders, but there was one major hurdle. Turkish President Recep Tayyip Erdogan said he did not look at the two countries’ accession to NATO “positively” and accused them of hosting Kurdish “terrorist organizations”.
Under NATO rules, only one member state can veto the membership of a new applicant.
However, a major diplomatic breakthrough between the three countries took place on Tuesday at the NATO summit in Madrid. Turkey signed a trilateral memorandum with Finland and Sweden, raising their opposition and giving them the official welcome to join the bloc.
“In NATO, we have always shown that whatever our differences, we can always sit down, find common ground and solve any problem. NATO’s open door policy has been a historic success,” the secretary said. NATO General Jens Stoltenberg to journalists in Madrid.
On Wednesday, NATO formally invited Sweden and Finland to join, initiating a multi-stage process that will end with both full member countries.
What happens next?
Stoltenberg said Wednesday that he expects Sweden and Finland to become members of the military alliance quickly.
The invitation triggers a seven-step membership process. Key moments on this path include talks between NATO and candidate countries. Candidates must formally accept the obligations of accession, and then the current member states sign an Accession Protocol, before ratifying it individually at home.
“We need a ratification process in 30 parliaments, which always takes some time, but I also hope it goes pretty fast because the allies are willing to try to get this ratification process going as soon as possible,” Stoltenberg explained on Wednesday.
After that, the candidate country is formally invited to accede to the Washington Treaty, the founding document of the alliance.
NATO has an “open door” policy: any country can be invited to join if it expresses an interest, as long as it is able and willing to uphold the principles of the bloc’s founding treaty.
The ratification process usually takes about a year, from the signing of the Protocol of Accession by existing members to the country’s accession to the Washington Treaty.
But the war in Ukraine has added an unprecedented urgency to the accession of Sweden and Finland, and the timetable could be accelerated accordingly.
How have leaders reacted?
U.S. President Joe Biden praised the breakthrough with Turkey, saying it sent a clear signal to Russia that NATO was united and growing.
“Sweden and Finland’s decision to move away from neutrality and the tradition of neutrality to join the NATO alliance will make us stronger and safer and NATO stronger,” Biden said. “We send an unmistakable message in my opinion … that NATO is strong, united, and the steps we take during this summit will further increase our collective strength.”
Biden said the accession of the two Nordic countries was a sign that Putin’s goals had failed.
“Putin was looking for the Finnishization of Europe,” he said, referring to the so-called dynamics of Finnishization that saw Russia dominate its foreign neighbor’s foreign policy for decades. “It will achieve the NATOization of Europe, and that’s exactly what I didn’t want, that’s exactly what needs to be done to ensure Europe’s security. And I think it’s necessary,” Biden said.
The move was welcomed by the countries that make up NATO’s eastern front, many of whom have expressed concern that they could be next in Russia’s sights if successful in Ukraine.
Estonian Prime Minister Kaja Kallas said the move was “significant” and Lithuanian President Gitanas Nauseda described it as “wonderful news”.
What does NATO membership mean?
The reason most countries join NATO is because of Article 5 of the North Atlantic Treaty, which stipulates that all signatories consider an attack on one member as an attack on all.
Article 5 has been the cornerstone of the alliance since it was founded in 1949 as a counterweight to the Soviet Union.
The purpose of the treaty, and of Article 5 specifically, was to deter the Soviets from attacking liberal democracies that had no military force. Article 5 ensures that the resources of the entire alliance, including the massive U.S. military, can be used to protect any member nation, such as smaller countries that would be defenseless without their allies. Iceland, for example, has no standing army.
Former Swedish leader Carl Bildt told CNN that he did not expect new large military bases to be built in either country if they joined. He said joining the alliance would likely mean more training and joint military planning between Finland, Sweden and the current 30 members. Swedish and Finnish forces could also participate in other NATO operations around the world, such as those in the Baltic states, where several bases have multinational troops.
“There will be preparations for contingencies as part of deterring any adventure the Russians may be thinking about,” Bildt said. “Real change will be quite limited.”
Why have Finland and Sweden not already joined NATO?
While other Nordic countries such as Norway, Denmark and Iceland were original members of the alliance, Sweden and Finland did not join the pact for historical and geopolitical reasons.
Both Finland, which declared independence from Russia in 1917 after the Bolshevik revolution, and Sweden adopted neutral foreign policy positions during the Cold War, refusing to align with either the Soviet Union or the United States.
Sweden’s policy of neutrality dates back to the early 1800s, when the country remained firmly out of European conflicts. Its king Gustav XIV formally adopted this neutral status in 1834, according to NATO, and Sweden declared a policy of “non-belligerence” during World War II, allowing Nazi troops to cross their lands into Finland. , while accepting Jewish refugees.
Sweden chose to maintain its neutral status once the war was over.
Historically, Finland’s neutrality has proved more difficult, as it shared a long border with an authoritarian superpower.
A Finnish-Soviet treaty known as the Friendship Agreement, signed in 1948 and sometimes extended over the decades, banned Finland from joining any military alliance deemed hostile to the USSR, or allowing a Western attack through of Finnish territory.
To keep the peace, the Finns adopted an agreement sometimes called Finnishization, in which leaders occasionally acceded to Soviet demands. The term was coined during the Cold War and has been applied to other countries in which a superpower exercises control over the smaller neighboring states.
The balancing acts of both countries effectively ended the collapse of the Soviet Union. Sweden and Finland joined the European Union together in 1995 and aligned their defense policies with the West, avoiding joining NATO.
How the invasion of Russia changed everything
Sweden and Finland have been making progress towards the West for security reasons since they joined the EU shortly after the end of the Cold War. But Russia’s invasion of Ukraine drastically accelerated that process, pushing them to pull the trigger for NATO membership.
If the Kremlin were willing to invade Ukraine, a country of 44 million people, a GDP of about $ 516 million and armed forces of 200,000 active soldiers, what would prevent Putin from invading smaller countries like Finland or Sweden?
“Everything changed when Russia invaded Ukraine,” Finnish Prime Minister Sanna Marin said in April. “The mentality of the people in Finland, also in Sweden, changed and changed very dramatically.”
Since the invasion of Ukraine in February, Finnish public support for NATO membership has gone from 30% to almost 80% in some polls. Most Swedes also approve of their country joining the alliance, according to opinion polls.
How has Russia reacted?
Russia criticized the May decision of Finland and Sweden to seek to join the alliance. His Deputy Foreign Minister Sergei Ryabkov said at the time that the measure would be a “mistake” with “far-reaching consequences,” according to Russian state news agency TASS.
This followed similar threats from senior Moscow officials. Kremlin spokesman Dmitry Peskov said after the announcement that “NATO expansion does not make the world more stable and secure.” He added that Russia’s reaction will depend “on how far and at what distance from our borders the military infrastructure will move.”
Russia currently shares some 755 miles of land border with five NATO members, according to the alliance. Finland’s accession would mean that a nation with which Russia shares an 830-mile border would formally align itself militarily with the United States.
The incorporation of Finland and Sweden would also benefit the alliance, which would frustrate Russia. Both are serious military powers, despite their small population.
But Putin has so far been quieter in his rhetoric than some of his officials. Last month he said “Russia has no problems with these states,” adding that NATO expansion “does not pose a direct threat to Russia.”
“But the expansion of military infrastructure in this territory will certainly provoke our response,” he added to the Organization of the Moscow Collective Security Treaty. “We’ll see what happens based on the threats that will be created for us.”