The breakthrough was made possible at the NATO summit in Madrid. This summit has become one of the most important meetings in the history of the military alliance.
Both countries are now expected to strengthen the eastern side of the block within a few months of Russia's invasion of Ukraine and soon become a full NATO member.
Here's everything you need to know why the move happened, what's next, and why it's important.
What is the latest development?
Sweden and Finland announced their intention to join NATO in May after Russia's invasion of Ukraine suddenly changed its attitude towards participation in the block.
The announcement was welcomed by almost all NATO leaders, but with one serious obstacle. Turkey's President Recep Tayyip Erdogan has accused him of containing Kurdish "terrorist organizations" and said he has not seen both countries "actively" participating in NATO.
NATO rules allow only one member country to deny membership in a new applicant.
However, the NATO summit in Madrid on Tuesday opened a major diplomatic breakthrough between the three countries. Turkey signed a trilateral memorandum of understanding between Finland and Sweden, dismissed opponents and officially welcomed them to join the block.
"At NATO, we have always shown that we can always sit down, find common ground and solve problems, whatever our differences. NATO's open door policy has been a historic success. "It was," said NATO Secretary General Jens Stoltenberg. Madrid journalist.
On Wednesday, NATO officially invited Sweden and Finland to begin a multi-step process that ends with full membership in both countries.
What will happen next?
Stortemberg said Wednesday that he hopes Sweden and Finland will become members of the military alliance.
Invitations trigger a 7-step accession process. Important moments along the way include discussions between NATO and candidate countries. Candidates must formally accept their membership obligations, after which current Member States will sign the Accession Protocol before ratifying it individually.
"30 parliaments need a ratification process. This will always take some time, but allies are ready to make that ratification process happen as soon as possible, so go pretty fast. I'm also looking forward to it, "explained on Wednesday.
The candidate country is then formally invited to join the CITES, the founding document of the alliance.
NATO has an "open door" policy. Any country of interest can be invited to participate, as long as it has the ability and willingness to support the principles of the Brock Creation Convention.
The ratification process usually takes about a year from the signing of the accession protocol by existing member states to the accession to the Washington Convention.
However, the war in Ukraine adds unprecedented urgency to the membership of Sweden and Finland, which can accelerate the timeline accordingly.
How did the leader react?
US President Joe Biden said he had sent Russia a clear signal that NATO was united and growing, praising the breakthrough with Turkey.
Sweden and Finland "The neutral tradition of joining the NATO alliance away from the neutrals will make us stronger, safer and stronger," Biden said. "I am sending an unmistakable message that NATO is strong and united. The steps we are taking at this summit will further strengthen our collective strength."
Biden said the accession of the two Scandinavian countries was a sign that Putin's purpose was backfired.
"Putin was looking for a Finnishization of Europe," he said, to the so-called Finnishization dynamics in which Russia had been dominant over its small neighbor's foreign policy for decades. Mentioned. "He's trying to get Europe NATO, and that's exactly what he doesn't want, and that's exactly what needs to be done to ensure Europe's security, and it's necessary. I think, "Biden said.
This move has been a joy to all the countries that make up NATO's Eastern Front. Many have expressed concern that if successful in Ukraine, it could come next at the Russian crosshairs.
Estonian Prime Minister Kaja Kallas called this step "important" and Lithuanian President Gitanas Nauseda called it "great news".
What do I need to join NATO?
Article 5 has been at the heart of the alliance since it was founded as a counterweight in the Soviet Union in 1949.
The point of the treaty, specifically Article 5, was to prevent the Soviet Union from attacking the under-military liberal democracy. Article 5 guarantees that the resources of the entire alliance, including the large US military, can be used to protect a single member, such as a small, unprotected country without an ally. For example, Iceland does not have a standing army.
Former Swedish leader Carl Bildt said he did not expect a new large military base to be built in either country if CNN joined. Joining the alliance probably means conducting more joint military training and planning among Finland, Sweden, and the current 30 members, he said. Swedish and Finnish troops can also participate in other NATO operations around the world, including the Baltic States, which have multinational forces at several bases.
"As part of stopping the adventures that Russians may be thinking, preparations for contingencies will be made," Bilt said. "Actual changes will be quite limited."
Why are Finland and Sweden not affiliated with NATO?
Other Nordic countries such as Norway, Denmark and Iceland were original members of the alliance, but Sweden and Finland did not join the agreement for historical and geopolitical reasons. did.
After the Bolshevik Revolution, Finland and Sweden, which declared independence from Russia in 1917, adopted a neutral foreign policy during the Cold War and refused to work with the Soviet Union or the United States.
Sweden has chosen to maintain its neutral status after the end of the war.
Finland's neutral nation has proven historically difficult because it shares a long border with authoritarian superpowers.
The Treaty between Finland and the Soviet Union, signed in 1948 and occasionally extended for decades, states that Finland will join a military alliance that is considered hostile to the Soviet Union, or that Finland It was forbidden to allow Western attacks through. area.
To maintain peace, Finns have adopted an arrangement, sometimes referred to as Finlandization. In this arrangement, leaders sometimes responded to Soviet demands. The term was coined during the Cold War and applies to other countries where superpowers dominate smaller neighbors.
The equilibrium between the two countries has virtually ended with the collapse of the Soviet Union. Sweden and Finland joined the European Union in 1995 and gradually adapted their defense policies to the West, avoiding full accession to NATO.
How Russia's aggression changed everything
Sweden and Finland have been on security issues since joining the EU shortly after the end of the Cold War. I'm heading west. However, Russia's invasion of Ukraine dramatically accelerated the process and urged them to trigger NATO accession.
If the Kremlin is willing to invade Ukraine (44 million, GDP is about , $ 155 billion, army is 200,000 active troops), what is Putin? Invade small countries like Finland and Sweden.
"Everything changed when Russia invaded Ukraine," Finland's Prime Minister Sanna Marin said in April. "Even in Finland and Sweden, people's thinking has changed dramatically."
Since the invasion of Ukraine in February, Finnish people's support for NATO membership has been partly polled. It jumped from about 30% to about 80%. According to polls, the majority of Swedes also allow their country to join the alliance.
How did Russia react?
Russia has condemned Finland and Sweden's May decision to join the alliance. According to Russia's national news agency TASS, its deputy foreign minister, Sergei Ryabkov, said the move was a "mistake" with "widespread consequences."
It followed a similar threat from high-ranking Moscow officials. Kremlin spokesman Dmitry Peskov said after the announcement, "The enlargement of NATO does not make the world more stable and secure. According to the alliance, Russia's reaction is" how far and how much military infrastructure is on the border. It depends on "approaching?" According to the
alliance, Russia currently shares a border of about 755 miles with five NATO member states. Finland's accession means that countries with Russia's 830-mile border will formally militarily cooperate with the United States.
The addition of Finland and Sweden also benefits the alliance and irritates Russia. Despite its small population, it is a serious military force.
But Putin has so far been more silent in his rhetoric than some officials. Last month he said, "Russia has no problems with these states." The enlargement of NATO "does not pose a direct threat to Russia."
"But the expansion of military infrastructure to this territory will certainly trigger our response," he said in Moscow. Added by the Collective Security Treaty Organization. "We will see what happens based on the threats created for us."
Why Russia is so opposed to NATO mosquito.
Putin sees the alliance as a defense against Russia, even though much of the post-Soviet era focused on issues such as terrorism and peacekeeping.
Before Putin invaded Ukraine, he said that NATO was too close to Russia and that some countries that were adjacent to Russia or former Soviet countries joined in the 1990s. Revealed his belief that he needed to return to the border. Military alliance.
Ironically, his invasion gave the alliance a new purpose and increased its strength.
Correction: According to the World Bank, this story has been updated to correct Ukraine's GDP, which was $ 155.5 billion in 2020.