They came in winter, when the nights were short and the ground was hard. They came by land and air, perhaps 760,000 of them, with tanks and bomber planes. When it started, the world imagined that they’d conquer with ease. But the world was wrong. The defenders, fighting for their homes and their country, beat back a complacent foe, ambushing their armour and deploying snipers to pick off their officers in the snow. The attackers, increasingly demoralised with a war they didn’t fully understand, began to mutiny, ignoring the calls of their leaders to launch yet more suicidal assaults. The defenders, for their part, were jubilant. “So many Russians,” went one common saying. “Where will we bury them all?”

In case you haven’t guessed, this does not, in fact, describe Moscow’s shambolic invasion of Ukraine in February 2022. For though they share much – including the aggressors themselves – that popular phrase was first uttered not in Kyiv, but in Helsinki.

The Winter War, which the Soviet Union waged against Finland from November 1939, culminated in the humbling of an imperial power. And now, with another Russian neighbour reduced to ashes, the Nordic country must reflect on its security once more. So it was that in April 2023, Finland abandoned decades of neutrality and became the 31st member of Nato. Further west, along the Baltic Sea, Swedish politicians soon hope to achieve the same goal.

Altogether, it’s the biggest expansion of Nato since 2009 – and promises to have dramatic consequences, everywhere from geography to defence procurement, for both the new arrivals and the alliance as a whole. All the same, this expansion has hardly come from nowhere. Since the end of the Cold War, after all, both Sweden and Finland have gradually increased their military collaboration with other like-minded democracies. Though proper Nato membership is certainly significant, in other words, it’s perhaps slightly less revolutionary than what the press releases imply.

The Finn’s red line

As the experience of the Winter War so vividly evokes, Nordic countries have long had to be wary of the threat to the east. But for much of the 20th century, Finland and Sweden dealt with that threat through subtle diplomacy and rugged isolation. “While friendly relations with the Soviet Union were emphasised in official governmental expressions for decades,” explains Dr Tommi Koivula of the Finnish National Defence University, “militarily, Finland sought to prepare against a possible attack by the one and only potentially hostile country: the Soviet Union.”

830 miles
The length of Finland’s border with Russia. 
European Commission

Aloof from the overtures of both Nato and the Warsaw Pact, in short, Finland instead defended its borders through massive conscription, encompassing upwards of 700,000 men by the 1970s. Sweden, for its part, remained somewhat closer to the US, tolerating the presence of American nuclear submarines off its waters. Even so, the prospect of joining Nato was always remote for as long as the Iron Curtain existed. With the collapse of the Soviet Union in the early 1990s, however, everything changed. Pax Americana was the order of the day – and the Nordic countries reacted in kind.

“The threat of major wars in Europe is now less acute,” says Henri Vanhanen from the Finnish Institute of International Affairs, meaning that both Sweden and Finland could pursue their geopolitical interests more explicitly. In the first place, that meant joining the European Union, something both countries did in 1995. From there, Helsinki and Stockholm became more involved in humanitarian missions abroad, notably in hotspots like Kosovo. That was shadowed by closer collaboration with Nato itself. As Lieutenant General Carl-Johan Edström, head of joint operations at the Swedish Armed Forces explains, his country has been an ‘Enhanced Opportunity Partner’ with Nato since 2014.

Even so, opinion polls as late as 2021 showed that neither Swedes nor Finns seemed keen on becoming fully-fledged Nato members – hardly surprising when so-called ‘armed neutrality’ had served them well for so long. Yet, though Sweden abandoned military entanglements as far back as 1815, Russia’s dramatic invasion of Ukraine exploded public perceptions. According to one November 2022 survey, to give one example, 78% of Finns were positive about Nato membership, with over half happy to host alliance bases on Finnish soil.

Clearly, much of this shift can be explained by the ferocity of Putin’s actions, as well as by the collective security Nato membership offers. But perhaps more important are the specific threats voiced by Russia towards its neighbours. In particular, Edström highlights President Putin’s comments, made just a few months before his attack on Ukraine, that “small countries outside of Russia” shouldn’t be able to decide if they want to join Nato. That’s echoed, the officer continues, by other worries, from cyberattacks to long-range weapons.

Swede on

Finland is now an official Nato member. Sweden has lagged behind somewhat: Turkey, another Nato ally, is proving slow to approve Stockholm’s application because the country harbours Kurdish militants, which Ankara considers terrorists. But the question remains: once both countries do officially join the alliance, what will they contribute? Perhaps the easiest way to understand things here is geographically. “If you look at the location, it’s both a Nordic and a Baltic country,” says Vanhanen. Fair enough. Boasting a direct border with Russia 830 miles long, Finnish membership certainly helps Nato strategists in Brussels, not least given the country’s expertise in Arctic warfare. Edström, for his part, argues that both new members bolster Nato’s “operational depth” in other ways. That’s doubly true when you consider the Swedish island of Gotland, prominently located in the Baltic Sea and acting like a “very big” aircraft carrier for potential operations in the region.

Beyond the sweep of geopolitics, both Sweden and Finland bring more practical advantages to the alliance. Consider, for instance, the region’s defence industry, with conglomerates like Saab already receiving 58% of sales revenue from exports overseas. Finland offers similar expertise in technologies as varied as armoured vehicles and turreted mortars, with integration into Nato made easier by the fact that interoperability has been a shared principle for years. And if both countries have gradually shaken off their mantle of neutrality, their self-sufficient histories could prove useful too. “The Finnish concept of comprehensive security – our guideline for security and preparedness activities in different sectors of society – aims to safeguard the vital functions of society through cooperation between authorities, business operators, organisations and citizens,” says Koivula, adding that a robust civil society is helpful in combatting disinformation, as well as the “hybrid influence” epitomised by the ‘little green men’ that appeared in Crimea during Russia’s 2014 invasion.

Not, of course, that Finland and Sweden are only joining Nato for what they can offer. Vanhanen, for his part, highlights the “nuclear umbrella” – a reasonable point when the US has over 5,000 such weapons, even as France and the UK operate submarine-based deterrents of their own. There are more practical benefits of membership, too. For Koivula, air support in the event of a Russian attack is one advantage here, as is Nato ability to keep Baltic supply lines open. Given their traditionally close relationship, meanwhile, Edström equally stresses the ways in which Finland and Sweden can support each other under the wider Nato banner, notably in the “high north” near the Arctic Circle. There’s evidence, in fact, that this is already happening. In June 2023, 6,500 Finnish troops hosted exercises with roughly 1,000 soldiers from the UK, Norway, Sweden and the US. Significantly, the training session happened at Rovajarvi – a military site just two hours from the Russian frontier.

Making things Baltic

With Russia’s 2022 invasion a shock to even the most hardened of military analysts, it’d be foolish to predict the future of European geopolitics. Yet, speak to the experts and they seem buoyant about what Nato membership can offer both Sweden and Finland – and what they can offer Nato in turn. Koivula, for instance, predicts a strengthening of bilateral relations between Finland and the US, even as Baltic and Nordic militaries become a “more prolific grouping within Nato” given the rising Russian threat. Vanhanen makes a similar point. “I think Finland will be [working to ensure] that Nato will be able to have functioning command structures in Northern Europe,” he says, “that the division of tasks and labour in terms of security and defence among Nordic countries, the Baltic countries, Poland and Germany is fair and serves a clear purpose.”

You’d imagine that prior experience should flatten these concerns. For as the long-standing focus on interoperability implies – and Edström confirms – both Finland and Sweden were already well on the way to becoming honorary Nato members. “When it comes to the tactical level,” he says, “interoperability is already there, and the way we are running tactical operations. On a unit level, we are very much already interoperable. So that will not change that much.” Having said that, Edström does emphasise that some things will need to be tweaked. One area is connectivity. Another is operational planning: Sweden may have been an Enhanced Opportunity Partner, but that hardly meant they were in the room when Nato campaigns were being organised. Yet, if past experience can be relied on, it seems clear that both new members should fit neatly into the alliance they spurned for so long, even as Ukraine’s own war enters its third long winter.