On 4 April 2023, Finland’s Blue Cross Flag was hoisted at NATO Headquarters, marking the nation’s entry into the Alliance. Finland’s formal accession to NATO was the culmination of an 11-month membership path that was triggered following Russia’s unprovoked war of aggression against Ukraine in February 2022. The overwhelming majority of Finns supported their nation’s NATO membership, and many toasts were raised that day in early spring. Though joining the Alliance without Sweden – which was left to wait for the completion of its own accession process - put a slight damper on the festive occasion.

Ceremony marking the accession of Finland to NATO during the meeting of NATO Ministers of Foreign Affairs on 4 April 2023, Brussels, Belgium © NATO

For Finnish officials and other national security professionals, Russia’s full-scale assault and Finland’s ensuing NATO bid were career-defining events. Carrying out a doctrinal change amid a tense security situation was a formidable and high-stakes task, which was further compounded by unprecedented media attention. Fortunately, the conditions for Finnish accession ultimately proved favourable. The Alliance welcomed Finland with open arms, Russia was either incapable or unwilling to retaliate, and, importantly, the accession united Finns across the political spectrum.

I followed the dramatic NATO process as an analyst at the Finnish Institute of International Affairs (FIIA). The war and the resulting transformation in Finland’s foreign and security policy were momentous events that profoundly shaped FIIA’s work. For me, it meant casting aside ongoing projects and devoting my full attention to the unfolding developments in European and Finnish security. Since early 2022, I have published several studies and articles, given hundreds of interviews, supported policymaking in parliamentary hearings, travelled extensively to explain the Finnish policy turn, hosted numerous foreign expert groups and fact-finding missions in Helsinki, and spoken in dozens of events in Finland and elsewhere. Many of these efforts have been collegial and carried out with my brilliant FIIA co-workers.

Dr Matti Pesu in Puheenaihe podcast studio. Photo courtesy of Puheenaihe Podcast.

In hindsight, the Finnish journey to NATO may look rather straightforward and logical. On the contrary, its membership bid was an abrupt reaction to Russia’s full-scale invasion of Ukraine. The ensuing national deliberation process was also fraught with uncertainties. By taking a personal approach, interweaving my own activities and reasoning with the historic developments in Finnish security policy which took place in 2022-2023, I hope to demonstrate that Finland’s policy shift was indeed highly contingent upon developments in the domestic landscape and international security environment before and after the Russian invasion, not a pre-determined outcome of the attack.

Dark clouds over Europe

The beginning of Finland’s journey to NATO can be dated back to the early 1990s. It joined the Partnership for Peace Programme in 1994 and immediately became a contributor to the Alliance’s crisis-management operations. From late 1990s to early 2010s, the country subsequently took several important steps that brought it closer to NATO.

However, instead of examining the longue durée of Finland’s path to NATO, let’s start from the fall of 2021 when Russia began to amass troops close to Ukrainian borders. Moscow ominously punctuated the unprecedented build-up with demands for ‘security guarantees’ against further NATO enlargement. In hindsight, these developments over the October to December 2021 period set the stage for Finland’s NATO bid. Russia’s increasingly vocal appeals for a sphere of influence were seen as a direct threat to Finland’s room for manoeuvre. New politicians came out in favour of NATO membership. The Finnish media was suddenly teeming with analyses about what it would mean for Finland to join NATO. In early 2022, foreign media outlets also picked up on the potential evolution in Finland’s foreign policy, which further magnified the ongoing discussion inside the country.

Although the Finnish political leadership defended the status quo and called for composure, the debate did not evade the Finnish public. In fact, the percentage of Finns with no definite view on NATO membership started to grow at the expense of those opposed. It seemed that the active debate rendered a greater proportion of the population amenable to reconsidering their stance on NATO accession.

My views on the potential change in Finnish foreign policy were cautious. As a young student and scholar, I strongly advocated for Finland’s NATO membership. When I got older, my zeal for the cause somewhat flagged. Helsinki had built an extensive network of defence partnerships concentrating on territorial defence, and maintained strong national military capabilities. Russia had also become more aggressive and unpredictable. In a nutshell, although I thought that militarily it would make sense to join the Alliance, I was also of the opinion that membership in the Alliance was not worth exposing the country to severe security risks. In the early weeks of 2022, I was - without a doubt - in the wait-and-see camp.

From that vantage point, I did my best to contribute to the discussion around Finnish membership in NATO. In an op-ed piece in the largest Finnish daily, I claimed that the unprecedented international speculation around Finnish NATO membership was a symptom of ambiguity in Finnish strategic communication efforts, which should clarify Finland’s unique role as a non-allied contributor to collective defence in Northern Europe. Furthermore, as late as mid-February, I argued in a prestigious national security outlet that Finland was unlikely to join NATO anytime soon, but it may consider membership if Russia became more aggressive, if the United States exerted strong influence, or if Sweden decided to join. The article had its merits, but the main argument did not age well.

The full-scale assault as a transformative shock

Early on the morning of 24 February 2022, I was in a taxi on my way to the television studio. I was invited to discuss the likelihood of potential Western security guarantees for Ukraine – a question that was addressed at the Munich Security Conference earlier in February. While in the taxi, I decided to check the news and realised that the day’s discussion would no longer be about Ukraine’s place in European security structures. The Russian invasion had begun.

Ukrainian troops responding to a Russian rocket attack on a shopping mall on 21 March 2022, Kyiv, Ukraine. © Getty Images

Russia’s full-scale attack on Ukraine turned a new chapter in European security. The Finnish top leadership immediately condemned Russian aggression and announced that Finland would start seeking out new measures to improve its security. The invasion was also a professional turning point for security experts. Suddenly, there was an insatiable public desire for information about the war, and the air was filled with tangible concerns regarding Finnish national security. During my commute to work, I overheard people discussing the Russian attack and Finland’s alternatives. The FIIA was fully focused on the war and the parallel discussions on Finnish security. The media interest by the national and foreign press was unprecedented. My only job was to follow the unfolding events and offer my expertise to the ongoing public discussion and policy deliberations.

On 28 February, four days after Russia launched its invasion, the Finnish Broadcasting Company released a significant survey. For the first time in Finland’s history, 53 percent of the population were in favour of NATO membership. The poll was striking. As late as December 2021, 51 percent of Finns were against joining NATO – a figure well in line with the previous surveys conducted since the mid-1990s. The U-turn in popular views gave dramatic urgency for the national policymaking process.

My initial reaction to the changed public mood was hesitant. I considered the transformed popular opinion to be gung-ho, and I was also concerned that the public was asking leadership for something that would not - under prevailing circumstances – be realisable. I also underestimated the transformative effect that the turnaround in citizens’ views would eventually have on policymakers’ perceptions on the desirability of NATO membership.

As a researcher, I always try to keep an analytical distance to my scholarly interests. There were, however, moments during the spring of 2022 when the sheer historicity of events just astonished me. When the Office of the President of the Republic of Finland announced that President Sauli Niinistö would travel to Washington D.C. to meet President Joe Biden, I got chills. I thought it incredible that the US president would receive his Finnish counterpart barely a week after the launch of a major war in Europe. I shared the release with my colleague asking whether he had seen the news. “They are going to do it now”, he said. It turned out to be an accurate prediction that the trip would initiate Finland’s bid to the Alliance.

President of the United States Joe Biden, and President of Finland Sauli Niinisto meet in the Oval Office at the White House in Washington, US, 4 March 2022. © Reuters

The main objective of the visit on 4 March 2022 was indeed to inquire about US views on and possible concrete support for Finland’s accession to NATO. The visit kick-started an internal policymaking process, and by mid-March, there was a shared understanding among Finnish policymakers that the country was on its way to NATO. The timeline, however, remained unclear.

I followed these events intently, while simultaneously pondering my own views and preferences. I vividly remember the moment in the early days of March when it struck me that not seeking NATO membership would be a bigger risk under the circumstances than the status quo. On 10 March, I posted a Twitter thread – which I called ‘the Long Telegram’ – where I urged Finland to pursue NATO accession though the process may be fraught with risks and membership may not be realistic in the immediate future. In my view, the timing of Finland’s application was of the essence.

The time from deliberation to making the actual decision was considerably shorter than I initially thought. Despite the considerable speed, there was nevertheless impatience in the Finnish public debate. Many commentators criticised the leadership for dragging its feet. I was sympathetic to Finland’s patient strategy of reaching a solid national consensus, securing strong Allied support for the eventual bid, and coordinating with Sweden. The strategy worked remarkably well, and on 18 May, the Finnish and Swedish ambassadors to NATO handed in their respective applications to Secretary General Jens Stoltenberg.

NATO Secretary General Jens Stoltenberg displays the applications for membership to NATO submitted by Finland and Sweden on 18 May 2022, Brussels, Belgium.
© Johanna Geron, Pool via AP

Long months before the culmination

Finland and Sweden were invited to join the Alliance at the Madrid Summit on 29 June 2022. Accomplishing this step calmed the atmosphere in Finland, although interest in Finland’s path to NATO remained high in the country and around the world. Finns followed Allied ratifications closely, and each approval was a cause for small celebration.

The beginning of the new leg on Finland’s NATO journey changed the focus of my analytical work. Now, the most important task was to start thinking about the potential contours of Finland’s eventual NATO policy and conceptualising its role in the Alliance. In December 2022, my colleague Tuomas Iso-Markku and I published an extensive report on Finland’s evolving NATO policy. It was extremely motivating to carry out pioneering research on such a significant subject and I am still proud of this well-received study.

Towards the end of 2022, it started to look more likely that Finland may be ratified before Sweden, triggering a lively national debate on whether Helsinki should move ahead with its NATO membership before Stockholm. I argued that proceeding in step with the Swedes must be the absolute priority, and a solo entry should be considered only if it did not harm Finland’s relations with the Alliance and with Sweden. When Finland did eventually decide to join the club before its neighbour, I, along with my colleague, felt it necessary to explain the grounds for Finland’s decision to our Swedish audiences. After all, Finland’s relationship with Sweden is its most valuable bilateral bond. Mutual trust between the two countries should therefore be preserved and cultivated.


If one takes a longer view, Finnish NATO membership may appear a logical final step in the nation’s lengthy journey to Western political and military structures. To some extent, this is true. However, with a closer look, the decision to join NATO was an abrupt and unexpected reaction to Russia’s war of aggression. In other words, Finland’s accession to the transatlantic Alliance was an undetermined outcome of particular factors in the Finnish political landscape, and in the international security environment. Had public opinion not changed or had Russia been more successful on the battlefield, Finland might have considered it too uncertain and risky to join NATO.

Dr Matti Pesu in Berlin. Photo courtesy of Kukka-Maria Kovsky.

I was fortunate to witness the historic transformation of Finland’s foreign and security policy from a close distance. To a certain degree, I was even a participant in the national deliberation process in my expert capacity. It was an instructive and sobering experience. On the one hand, the sudden and unexpected developments in Finnish and European security taught me a great deal of humility when it comes to predicting the future. On the other hand, I am more confident than before that analysts play important roles in relation to policymaking and informing society. I joked that for once, I felt relevant to society.

My firm view is that joining NATO was the right thing to do. It significantly bolsters Finland’s security. Moreover, at no other point in Finland’s history could the decision have been made in a way that would have united the Finnish people. This was the case in spring 2022. And this national unity gives a firm foundation for Finland’s emerging role in NATO.