Finland has walked a political tightrope between Moscow and the West for decades. But that could be about to end

Finland’s Prime Minister Sanna Marin has said that her country will be deciding on whether to join NATO within weeks. This could also propel neighbouring Sweden to do the same.

It would mark a dramatic U-turn for the country to join NATO and could anger Putin.

The Nordic nation shares a land border with Russia and has been careful in its foreign policy. During the Cold War, the policy of neutrality was adopted by the country. In the early stages of World War II, the Finns successfully repelled a Soviet invasion.

Russia's invasion of Ukraine could end its neutrality, which is cherished by many Finns.

Jacob Kirkegaard, a senior fellow at the German Marshall Fund of the United States, told CNBC that the idea of forced neutrality between East and West would be put to an end by the accession of Finland to NATO.

Russia's actions in Ukraine have forced previous neutral countries to either commit fully to NATO or not.

One of the reasons given by the Kremlin for its invasion of Ukraine was that Russia was against any NATO expansion. Volodymyr Zelenskyy, the president of Ukraine, had been vocal about his desire to join the alliance before the invasion, but has since conceded that it is now unlikely.

NATO nations have supported Ukraine with military equipment, but they have refused to send troops as this would put Russia and the West at war. An attack on one member of NATO is considered an attack on all of them.

Sanna Marin said last week that her country would make its decisions very quickly.

Opinion polls show that a majority of Finns are in favor of joining NATO. Alexander Stubb said Thursday that his country would apply for NATO membership in May.

NATO would likely benefit from the geographical location of Finland. The country would be welcomed by its secretary general.

The risks in joining the alliance are also aware of.

In a report to the Finns Parliament in April, the Foreign Ministry said that if it applied for NATO membership, it should be prepared for extensive efforts to exercise influence and risks that are difficult to anticipate.

If NATO membership were to go ahead, Russia would have to balance the situation.

It is possible that Sweden will follow in the footsteps of Finland and join NATO.

Sweden's Prime Minister said her country was doing the same analysis as Finland.

Finnish entry into NATO will cause Sweden to join at the same time. Kirkegaard said this ends several centuries of neutrality for Sweden and adds to NATO a major military power and arms producer.