Russia’s invasion of Ukraine has destroyed the 30-year post-Cold War order in Europe. Among its most significant and unexpected geopolitical effects is that Finland, long a nonaligned country, will likely soon join NATO, probably followed by its similarly nonaligned neighbor, Sweden. Finland shares an 830-mile border with Russia, and the Finnish capital of Helsinki is closer to Russian President Vladimir Putin’s hometown of St. Petersburg than it is to Stockholm. A NATO that includes Finland will more than double the alliance’s land borders with Russia.

Fear of Russia isn’t new for Finland. The country spent a century inside the Russian empire before gaining independence in 1917.  It lost a chunk of its southeastern territory to the Soviet Union following Joseph Stalin’s brief Winter War of 1939-40, and then it lost its autonomy under the so-called Finlandization policy of the Cold War. During those decades, Finns engaged in self-censorship and committed to a pro-Soviet foreign policy in return for not being occupied by Moscow. Following the collapse of the Soviet Union, Finland (like Sweden) made its Western identity clear by joining the European Union (EU) in 1995. Along with the rest of the EU, Helsinki also ratified the 2007 Lisbon Treaty, which commits each member to aid and assist any others who face an external military attack.

Starting in 2014, following Putin’s seizure of Crimea, Russia began menacing Finland again, in many ways treating Helsinki no differently than nearby NATO states. Moscow repeatedly breached Finnish air space, and twice interfered with Finnish scientific research ships operating in international waters. Yet Finland remained formally nonaligned, with a public afraid of antagonizing its powerful Russian neighbor. As recently as fall 2021, less than a third of the Finnish population supported NATO membership, a disposition that had held for decades. Finns instead preferred to serve as an economic and diplomatic bridge between Russia and the West. Indeed, Finland’s head of state, President Sauli Niinistö, knows Putin well (even playing hockey with him) and has long been seen as a political interpreter between Europe and Russia. While Finland’s bilateral trade relationship with Russia was badly affected by the 2020 pandemic—and has now been completely upended by EU sanctions—in prior years it often exceeded $10 billion, making Moscow one of Helsinki’s top five trading partners. Over 900 Finnish businesses had invested in Russia by 2019.

Russia’s unprovoked invasion of Ukraine, and especially growing reports of Russian atrocities and war crimes there, have quickly transformed Finnish public opinion. For the first time ever, a hefty majority of the Finnish public and most of Finland’s leading political parties now support NATO membership, and Finland is likely to apply for membership before the alliance’s June 29 summit in Madrid. (It will probably be followed by Sweden, with Stockholm waiting for Helsinki to act first.) Marking a historic shift in Helsinki’s strategic posture, NATO membership would give Finland the collective security guarantee of the world’s most powerful military alliance, backed by U.S. nuclear weapons. But it also could further upend Finland’s traditional economic relationship with Russia and expose the country to the risk of retaliation.

Location, Location, Location

In addition to their extensive shared land border, Finland and Russia are coastal neighbors along the Gulf of Finland. This gulf empties into the Baltic Sea, where the heavily militarized Russian exclave of Kaliningrad serves as home to Moscow’s Baltic Sea fleet. NATO dominates the southeastern shores of the Baltic Sea, with members Germany, Poland, and the Baltic states of Estonia, Latvia, and Lithuania. Yet Kaliningrad is wedged between Poland and Lithuania, and adding Finland and Sweden to the alliance on the northwestern shores of the Baltic would have significant geopolitical effects. For one thing, it would complicate Moscow’s ability to maintain sea and air access to Kaliningrad in the event of a war with the West, since the corridor linking the exclave and the rest of Russia would be surrounded by NATO members.

Gaining control of the Baltic Sea perimeter would also greatly ease NATO’s ability to defend its Baltic members in the event of a Russian attack. NATO planners have worried about this scenario ever since Russia’s seizure of Crimea in 2014, because Estonia and Latvia border Russia and have significant Russian ethnic minority populations, leaving them potentially vulnerable to Russian hybrid warfare operations. For example, Russian intelligence forces could conceivably launch an information warfare campaign that falsely accused authorities of persecuting ethnic Russians in Estonia, staging a fictitious request from locals that Russia send protective peacekeeping forces across the border. NATO planners are concerned that Russia could use Kaliningrad’s ships, aircraft, drones, and missiles—some of which are capable of carrying nuclear warheads—to deny the alliance easy naval and air access to Estonia and Latvia. Moreover, those states are connected by land to the rest of the alliance only along the tiny border between Lithuania and Poland—the so-called Suwalki gap—which is straddled by Kaliningrad on one side and Russian ally Belarus on the other, making wartime NATO land access equally risky. Under NATO’s current configuration, wartime defense of the Baltic states would probably involve high NATO casualties.

In the time between application and admission to NATO, Finland would not be covered by Article 5.

But the inclusion of Finland and Sweden, both of which border NATO member Norway, would alter the balance of power in the region. Finland lies just over 200 miles across the Gulf of Finland from Estonia and is already in the process of upgrading its air defense systems. Finland and Estonia have also launched a commercial initiative to connect Helsinki and Tallinn with a high-speed train tunnel under the gulf, making them a single urban area. Such a tunnel could presumably serve military purposes, too.

For Finland, though, joining NATO carries risks, putting the Finnish military on the frontlines of a newly critical border. Of special concern is the question of how Moscow will react to a formal request by Helsinki to join the alliance—there will likely be a gap of many months between Finland’s membership application and its official welcome into NATO. During that time, Finland would not yet be covered by NATO’s Article 5 collective defense guarantee, and Russia might be tempted to threaten or attack Finland, hoping that Finnish public opinion would once again turn against joining the alliance and short-circuit the membership process.

Hungarian Haggling

The geographic enlargement of NATO is not a new phenomenon. In Article 10 of its founding document, the 1949 North Atlantic Treaty, alliance architects foresaw that any capable European state that shared NATO’s security goals could be invited to join its initial 12 members. With North Macedonia’s accession in 2020, NATO now includes 30 states. Fourteen of them have joined since the end of the Cold War. In a 1995 document, NATO laid out the basic (if rather vague) requirements for new members, which have always been subject to political negotiation: a commitment to liberal democracy, rule of law, and democratic control over military forces; a market economy capable of contributing to the common defense; and the resolution of all outstanding ethnic and border disputes. Designed for former Warsaw Pact and other eastern European states undergoing Westernizing reforms, these requirements involve a cumbersome set of procedures and preparations, culminating in a unique and detailed “membership action plan for each aspirant.

Finland, with a constitutional democracy established in 1919, an advanced trading economy, and a highly capable military, meets all of the membership criteria with ease, placing it in a different category from other recent NATO aspirants. Helsinki’s armed forces are also a known quantity for the alliance. Since 1994, Finland has participated in NATO’s Partnership for Peace program, designed to build trust and interoperability between NATO and other countries through joint education, training, and force deployments. Finland has served on NATO-led missions in the Balkans, Afghanistan, and Iraq. It is also one of six “Enhanced Opportunities Partners” with which NATO has shared additional resources and information since the Russian seizure of Crimea. That year, NATO entered a host-nation support agreement with Finland, allowing the country to receive help from the alliance in the event of “disasters, disruptions and threats to security” and deepening its participation in NATO training and exercises. Since 2017, Helsinki has also coordinated with NATO on cyberdefense issues, and it has opened a Centre of Excellence for Countering Hybrid Threats in partnership with NATO and the EU. (While the concept of “hybrid threats” is not well defined, it can include everything from information warfare and political influence operations to the use of non-state armed actors, either with or without the use of regular military forces.)

For these reasons, NATO could easily create a fast-track accession procedure for Finland, possibly compressing the timeline to as little as a month. The same is likely to hold true for Sweden. Indeed, NATO foreign ministers discussed these potential new membership requests at meetings in early April that included their Swedish and Finnish counterparts, indicating that such a process may already have begun.

Nonetheless, Finnish accession to the alliance could still be delayed by the requirement of legal ratification by each of NATO’s 30 member states. In the most recent ratification case, North Macedonia, this process took nearly a year. While it appears that all NATO members want Finland to join, there is concern among some analysts that Hungary’s prime minister, Viktor Orban, might threaten to slow the process in order to gain some political quid pro quo—probably not from NATO per se, but from the EU. As a right-wing authoritarian nationalist known for his continuing overtures to Russia, Orban has sparred with Helsinki since 2019, when Finland held the rotating EU presidency and led hearings (mandated by the EU parliament) on whether Hungary should have its EU voting rights curtailed in light of Orban’s rule-of-law violations at home. Now the European Commission is threatening to withhold COVID-19 support payments to Budapest over accusations of government corruption and Orban’s anti-LGBTQ policies. Since not all EU members are NATO members, and since the EU and NATO serve fundamentally differing purposes, any demands by Orban to link the two could complicate the accession process and require extended diplomatic maneuvering.

Minding the Gap

A direct Russian military attack on Finland seems unlikely. According to unconfirmed video footage, Moscow has already begun moving additional heavy weapons systems and missiles toward the Finnish border in response to media reports about Finland’s likely membership bid. But Kremlin planners would likely think twice about crossing that boundary. Since 2014, Helsinki’s 280,000-member defense forces have been reconfigured to respond rapidly to Russian-style hybrid warfare. In early April, the Finnish government further authorized a one-time $2 billion surge in defense spending, a 70 percent increase over its usual annual military budget. The budget emphasizes border and air defense, and the increase may have been designed to push Finland over NATO’s goal for its members to spend two percent of GDP on defense. As Russian forces get bogged down in Ukraine, it is also doubtful whether Moscow has the capacity to take on an additional theater of operations.

But the Kremlin could choose to pressure Finland in other ways. It might try some kind of cyber or intelligence action against Helsinki to turn the Finnish public against NATO, for example. (In 2016, when Montenegro was poised for NATO membership, Montenegrin officials allege that Russian intelligence operatives made an unsuccessful bid to engineer a coup against the elected government there.) In early April, Finnish government websites faced a surge of denial-of-service attacks linked to Russia. For now, such attacks have been quickly overcome and seem mostly symbolic, providing a way to register Moscow’s displeasure at Finland’s discussions about joining NATO. Finland has so far been spared the ransomware and critical infrastructure attacks that have plagued other countries in Russia’s sights, but it could now be targeted that way, too. Finnish officials have warned the public about possible political influence and information warfare campaigns, perhaps using deep-fake video technology to invent stories of mistreatment of the tens of thousands of Russian citizens and Finnish citizens of Russian ancestry who live in the country.

The United States and its fellow NATO members can provide bilateral defense support for Finland during its vulnerable transition to NATO membership. Such assistance would likely focus on cyber and air defenses and would build on long-standing military relationships. Finland has been buying U.S. weapons for 30 years, and just weeks before the Ukraine invasion began, it signed a $9 billion agreement to purchase 64 advanced F-35 fighter jets. Helsinki also has a close military relationship with London, including as a member (alongside Sweden and six current NATO members) of the United Kingdom’s Joint Expeditionary Force, established in 2014 for rapid crisis response in the Baltics.

Russia could seek to pressure Finland through cyberattacks or disinformation campaigns.

At the same time, Finland has a card of its own to play in any pressure campaign from Moscow: its deep economic relationship with Russia. That relationship has deteriorated significantly since the war in Ukraine began. The Finnish economy has been hit hard by Western sanctions against Russia, as well as by decisions to halt trade by Finnish firms reluctant to be associated with Moscow. Given the extensive history of economic ties between the two countries, however, Finland can position itself as a crucial bridge for any future Russian efforts to reestablish a relationship with the West.

In fact, at least some members of the Russian political elite around Putin have a direct stake in Moscow’s economic ties with Finland: oligarchs Vladimir Potanin, Oleg Deripaska, and Roman Abramovich, who through their Nornickel firm control a nickel refinery in Harjavalta, Finland. The Harjavalta refinery is part of a major new joint venture with Germany’s BASF company to supply Europe’s lithium-ion electric vehicle market with batteries, using nickel and cobalt imported from Russia. In 2021, Nornickel was the world’s largest producer of high-grade nickel and a leading producer of cobalt, and the firm has not yet been sanctioned by anyone. The refinery gives Russia good reason to maintain working relations with the Finnish government, although of course the West’s commodities dependence makes that relationship a two-way street.

Offense or Defense?

Counterintuitively, Moscow may not perceive Finnish membership in NATO as a major new threat. No one is suggesting moving any NATO troops to Finland or establishing any new military bases there. If NATO changed its military posture in Finland to prepare for an offensive attack against Russia, Moscow would have plenty of advance warning. Indeed, despite Putin’s frequent statements to the contrary, NATO’s land borders with Russia may not even be the threat that worries the Russian military the most. A 2020 RAND study found that Russian military doctrine is instead focused on the ability of major Western powers to launch long-range airstrikes against Russia in situations where ground troops would likely be used mostly to mop up afterwards.

Moreover, Finland cooperates so closely with NATO that the Russian military already sees it as tied to the alliance. Russian defense analysts have noted Finnish cooperation in NATO military exercises and labeled them an effort to jointly contain Russia. As the Finnish ambassador to the United States, Mikko Hautala, has said, “We are basically as close to NATO as you can get without being a member.” Although Russian officials have threatened unspecified military and diplomatic consequences if Finland and Sweden join NATO—even raising the specter of nuclear escalation—Kremlin spokesperson Dmitry Peskov has clarified that Russia would not see such a step as an existential threat but rather a prod to rebalance Russian force positioning in its western regions.

It is impossible to know for sure how Putin and his military forces will react to a Finnish bid to join NATO. As Russia’s initially bungled invasion of Ukraine and frequent targeting of civilians there has shown, the Kremlin’s own motives these days seem less strategic and more emotional, hobbled by miscalculations and Putin’s apparent isolation, and driven by the Russian leader’s sense of rage against the West. Given Finland’s long-standing membership in the EU community and defense ties with NATO, to join the alliance officially seems more like a logical next step than a sea change, but Putin’s reaction remains unpredictable. In the face of that unpredictability, it is probably safer for Finland to be inside the alliance than out.

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  • KIMBERLY MARTEN is a Professor of Political Science at Barnard College, and a Faculty Member of Columbia University’s Harriman Institute and Saltzman Institute.
  • More By Kimberly Marten