### Instruction: What are the main points in this article
### Input: Today, Finland became the 31st member of NATO, ending its decades-long policy of neutrality. Foreign minister Pekka Haavisto handed over the official documents in Brussels to United States Secretary of State Antony Blinken.


Protestors at a February 2022 rally against Russia's invasion of Ukraine march past the statue of Tsar Alexander II in Senate Square in Helsinki.
Image: rajatonvimma.

Map of NATO members including Finland
The accession was marked by raising the Finnish flag at NATO's main office in Brussels, Belgium, while the NATO flag was raised in Helsinki.

Finland shares a 1,340 kilometers (833 mi)-long border with Russia. By joining NATO, it roughly doubled the length of NATO borders with Russia.

"Until now, we have defended our country alone," said Defense Minister Antti Kaikkonen. "From now on, we can rely on getting outside help should things get tough. And of course, we are ready to help should someone be in trouble."

Kremlin representative Dmitry Peskov said it was an "encroachment on our security and on Russia's national interests". He said Russia would closely monitor NATO activity in Finland and take "counter-measures".

"Finland's membership is not targeted against anyone. Nor does it change the foundations or objectives of Finland's foreign and security policy," read a statement by Finnish President Sauli Niinistö after the accession documents were transferred.

"President Putin had as a declared goal of the invasion of Ukraine to get less NATO. He is getting exactly the opposite," said NATO Secretary General Jens Stoltenberg. "Finland today, and soon also Sweden will become a full-fledged member of the alliance".

In the wake of Russia's invasion of Ukraine last year, public sentiment in Finland and Sweden, which were both non-aligned countries, shifted drastically, to 80% support in the former's case. On May 18, both nations submitted applications to join NATO. New members must have the support of all existing members before they can join.

The applications were held up by Turkey under Recep Tayyip Erdoğan, because Finland and Sweden have granted political asylum to members of the Kurdistan Workers' Party, which Turkey views as a terrorist organization. Last week, the Grand National Assembly of Turkey voted to approve Finland.

Sweden still has to obtain the approval of both Hungary and Turkey before it can join. Hungary objects to Sweden based on its criticism of Viktor Orbán's government. A far-right group in Sweden held a Quran-burning in front of the Turkish embassy in January, which was condemned by the Turkish government.

After Russia won the Finnish War over Sweden in 1809, Finland became a Grand Duchy of the tsarist Russian Empire. This lasted until the Russian Civil War started in 1917 and Finland declared its independence.

In 1939, the Soviet Union invaded Finland in a conflict called the Winter War. It ended with a treaty in 1940, under which Finland ceded territory to the Soviets. When Germany invaded the Soviet Union in 1941 during World War II, Finland entered the war on the side of Germany. It ended with an armistice in 1944, and Finland relinquished another province.

Under President Urho Kekkonen, Finland formally adopted a policy of neutrality in 1956.
### Response: Finland became the 31st member of NATO, ending its decades-long policy of neutrality. 
In the wake of Russia's invasion of Ukraine last year, public sentiment in Finland shifted drastically, to 80% support in the former's case.
'Sweden is next in line, however it has to overcome opposition from Hungary and Turkey.