Finland and Sweden have formally submitted applications to join NATO, the world’s most powerful military alliance, in a move that will redraw the geopolitical map of northern Europe.

The decisions of the two historically neutral countries come in response to Russia’s invasion of Ukraine, now on its 84th day.

But for the Nordic countries to join the 30-member alliance, all other NATO members must unanimously agree to accept them.

While Turkey has expressed reservations about their accession, Ankara is not expected to stand in their way.

NATO’s history and expansion to the east

The North Atlantic Treaty Organization (NATO) was founded in 1949 by 12 member states – Belgium, Canada, Denmark, France, Iceland, Italy, Luxembourg, the Netherlands, Norway, Portugal, the United Kingdom and the United States – and was formed to slow Soviet expansion and encourage political integration in Europe in the aftermath of World War II.

The 30-member alliance is intended to guarantee political and military protection and allow European and North American nations to discuss security issues.

In recent years, Russian President Vladimir Putin has sought guarantees from NATO that it would halt its eastern expansion and end military cooperation with non-member Ukraine and Georgia.

In February, Putin said Russia’s “special operation” in Ukraine was a way to stop NATO growth, which he saw as an intrusion.

NATO military operations

Article 5 of the NATO Treaty sets out the principle of collective defense as the core of NATO’s Charter. This clause means that an attack on an ally is considered an attack on all members.

Some of NATO’s notable military operations include a naval blockade and airstrikes during the Bosnian war, which lasted from 1992 to 1995.

In 1999, NATO launched an air campaign to force Serbian leader Slobodan Milosevic to withdraw his forces from Kosovo and end the conflict there.

Following the September 11, 2001 attacks on the United States, NATO invoked Article 5 for the first time and joined forces with US and British forces to fight the Taliban in Afghanistan.

During the 20-year war, 50 NATO and partner nations contributed forces to the missions in Afghanistan. At its peak in 2011, nearly 140,000 US and allied forces were in the country.

Throughout the war between Russia and Ukraine, Ukrainian President Volodymyr Zelesnkyy has called for NATO to establish a no-fly zone over Ukraine – an idea that the alliance has rejected because it escalates the conflict to a global one.

NATO and CSTO

On Monday, the President of Belarus, Alexander Lukashenko, called on the Russian-led Collective Security Treaty Organization (CSTO) to agree on Finland’s and Sweden’s NATO bid.

The CSTO was formed in 1992 with Armenia, Kazakhstan, Kyrgyzstan, Russia, Tajikistan and Uzbekistan signing the first treaty. In 1993, Azerbaijan, Belarus and Georgia joined. The Treaty entered into force in 1994.

It currently consists of six member states: Russia, Armenia, Belarus, Kazakhstan, Kyrgyzstan and Tajikistan.

Like Article 5 of the NATO Charter, Article 4 of the CSTO states that aggression against a State Party is seen as aggression against all members.

As a result, participating states can support the affected state with provisions such as military aid.

NATO military spending

In 2020, the United States spent $ 778 billion on its military – the largest military expenditure in the world – according to the Stockholm International Peace Research Institute (SIPRI), which accounts for 3.7 percent of the country’s gross domestic product (GDP).

Among NATO members, Britain is the second highest military spender, with $ 59.2 billion spent on its military in 2020, equivalent to 2.2 percent of its GDP.

Iceland does not have its own military and therefore its military expenditure is zero.

In 2020, Finland spent $ 4.1 billion on its military, which is equivalent to 1.5 percent of the country’s GDP, while Sweden spent $ 6.5 billion, 1.2 percent of its GDP.

NATO budget

For 2022, NATO’s military budget is set EUR 1.56 billion (USD 1.64 billion). Member States contribute to the budget based on a cost-sharing formula derived from each country’s gross national income.

The United States and Germany contribute equally with the highest share, a total of more than 30 percent of the military budget.

What would NATO look like when Sweden and Finland join?

The application process for Finland and Sweden to join NATO can take up to a year. But once they are members, it would mean that NATO forces could be located right next to the Finnish-Russian border at 1,340 km (833 km), which in turn extends the borders between NATO and Russia along northwestern Russia.

Putin believes the move is an escalation of military tensions. During a televised CSTO meeting, he said that “the expansion of military infrastructure” would “provoke our response”.

Bosnia and Herzegovina, Georgia and Ukraine have previously expressed their desire to join NATO. But after Russia’s invasion of Ukraine, Zelenskyy admitted in March that it was unlikely that Ukraine would be able to join NATO.