Within a few weeks, Russia's war of aggression on Ukraine has changed the security situation in northern Europe. Finland and Sweden, the two non-aligned countries in the region want to become NATO members as soon as possible. On 17 December last year, Vladimir Putin called for a new security order in Europe with a halt to future NATO enlargements and the withdrawal of allied formations from Eastern Europe. With its brutal war of aggression, the Kremlin has now achieved the opposite. It has united NATO, strengthened the Alliance's military presence near the conflict zone and made it palatable for two more countries to join.

The picture has changed decisively as a result of the cruel Russian war in Ukraine, Finland's President Sauli Niinistö stressed on 12 May, referring to his changed view of Finnish NATO membership. 'If someone asks why Russia now has to see Finland join NATO, I say it is self-inflicted. Look in the mirror.'

Niinistö, who knows Putin better than most, already made it clear in his New Year's speech that his country's choice of security policy path was solely the business of the Finnish people. At the turn of the year, a clear majority of Finns were still against NATO membership. After 24 February, on the other hand, Finnish MPs reported that many voters had sought contact and expressed support for a debate on a NATO option. In recent polls from 10 May, a full 76 per cent were in favour of membership.

Uniting against an aggressive Russia

The Finns have a very pragmatic and practical view of NATO: protection against an unstable Russia, with which they share a 1,340-kilometre border. And they have a completely different historical experience with Moscow than their Swedish neighbours. In the turmoil of the Russian Revolution, Finland declared its independence in 1917. Between 1939 and 1945, it experienced enormous human suffering and lost a great deal of territory in the fight against Stalin's USSR. After the war, Moscow imposed a pact of friendship, cooperation and assistance on Finland and it had to commit itself to non-alignment. Only with the fall of the Soviet Union in 1991 was Finland able to apply for EU membership.

Neither Finland nor Sweden felt secure enough under the security guarantee of Article 42(7) of the EU Treaty after joining the EU in 1995, but NATO membership was a long way off for both countries. For Sweden, it shakes the identity and self-perception left by 200 years of non-alignment and peace. But here, too, Russia's war in Ukraine strongly influenced public opinion and leading politicians. Swedish Prime Minister Magdalena Andersson said after the Riksdag decision to join NATO that it would have been very difficult for Sweden to stand alone as an outsider country in an increasingly tense security situation.

The strategic hole that characterises the North is plugged and replaced by a tactical 'depth' that facilitates the defence of the Nordic and Baltic states.

While Denmark has voted in a referendum on 1 June to lift its reservations about the EU's Common Security and Defence Policy. The strategic map of Northern Europe has thus changed completely within a few months. The Finnish and Swedish accession to NATO is a game changer. The strategic hole that characterises the North is plugged and replaced by a tactical 'depth' that facilitates the defence of the Nordic and Baltic states. With all five Nordic countries in NATO, the Baltic Sea becomes largely a NATO sea.

Both Sweden and Finland are politically stable democracies, well-entrenched constitutional states and militarily strong. A united North in NATO increases the Alliance's military capacity and collective defence readiness. The membership of the two countries will strengthen NATO as a community of values and increase the political weight of the North in the Alliance. The two countries' defence capability extends NATO's deterrence and its defence capability in a region of strategic importance to the Alliance. Intelligence cooperation will also be greatly facilitated and a better understanding of the situation will be possible.

A strong norther deterrence

In terms of military strategy, the Finnish and Swedish formations can be easily integrated into NATO. The armed forces of both countries are already NATO-compatible, having participated in multinational operations and exercises for decades in the Balkans, Afghanistan, and Norway, among other places.

In the next few years, the Nordic countries will build up a significant fleet of modern combat aircraft. In total, Norway, Finland and Denmark will then have about 150 F-35 fighter aircraft and Sweden a considerable number of JAS 39 Gripen. That is an impressive air military capability. With this comes significant potential for cost-effective cooperation in bases, logistics and training and education.

With Finland and Sweden in NATO, Norway - as the only Atlantic coastal state with a border with Russia and with responsibility for an enormous maritime area seven times larger than its mainland - receives considerable backing.

Adding Germany, the Netherlands, and the UK as part of the North Sea cooperation, Northern Europe then has approximately 250 to 300 F-35s plus the Swedish fighters. This creates a comprehensive and robust deterrence regime in Northern Europe. And it increases NATO's ability to protect the transatlantic link across the North Atlantic against Russian disruption strategies. The latter is a crucial point to ensure that formations and reinforcements from the US can reach Europe in case of crisis or war. It has often been said that Norway is 'NATO in the North'. With Finland and Sweden in NATO, Norway - as the only Atlantic coastal state with a border with Russia and with responsibility for an enormous maritime area seven times larger than its mainland - receives considerable backing.

Russia’s reaction

Russia, of course, does not like Finland's and Sweden's change of defence policy at all. Both countries have indicated that they - like Norway - want to attach détente elements to their membership, including renouncing the establishment of permanent NATO bases in peacetime and the stationing of nuclear weapons in their countries. In the short term, however, increased tensions with Russia are to be expected. However, Moscow has only limited military capabilities to influence the NATO enlargement process. A large part of Russia's formations are tied up by the war in Ukraine. But the Kremlin could of course use hybrid means, which many warn against. This could be a mix of cyber-attacks and border violations in airspace or in the Baltic Sea, as well as the spread of misinformation to stir up fear and insecurity.

Only when all 30 NATO countries have ratified the admission of the two countries will Sweden and Finland become members.

It also cannot be ruled out that Moscow is trying to influence the ratification process within NATO by putting pressure on individual member states. One can only speculate whether such an approach is behind the sudden objections Turkey has now raised against the fast-track admission procedure for the two countries envisaged by NATO Secretary General Jens Stoltenberg. The Turkish government claims that Sweden and Finland are 'a home for Kurdish terrorists'. They have made their agreement to the fast-track procedure conditional on a number of demands.

Only when all 30 NATO countries have ratified the admission of the two countries will Sweden and Finland become members, and only then will the collective security guarantees of Article 5 take effect. These are ultimately the main reason for the two countries applying for membership. Because de facto, after the many years of close cooperation with NATO, they can already be considered quasi 'semi-members'.