Finland and Sweden are “like guesthouses for terror organizations,” according to Turkey’s President Recep Tayyip Erdoğan. On Wednesday, as Finland and Sweden formally applied to join the North Atlantic Treaty Organization, they faced Turkey’s opposition—with Erdoğan accusing them of harboring members of the Kurdistan Workers Party, a militant organization committed to its region’s separation from the Turkish state. The objection to Finland’s and Sweden’s membership in NATO was impossible to ignore—given that support from all 30 of the alliance’s existing member states is required to admit new countries—but it was also more a diplomatic hurdle than a barrier for the alliance, with the two Nordic democracies now almost certain to join. It’s a priority for them and for the alliance as a whole. But it’s also a major historical shift, after decades—in Sweden’s case, two centuries—of non-alignment. What’s happening?

Susan Colbourn is a NATO historian and the associate director of the Triangle Institute for Security Studies at Duke University’s Sanford School of Public Policy. According to Colbourn, Finland and Sweden’s actions represent a huge shift with a complex history—and the latest illustration of how Moscow’s invasion has led to acute unintended consequences for President Vladimir Putin and his country. Although Putin is likely to seize on the prospect of NATO expansion to continue his longstanding rhetorical assaults on the alliance, his practical options to respond are limited—especially given Russia’s weakened global position following the Ukraine invasion. As Colbourn sees it, the extension of NATO to Finland and Sweden is transformative—and uncertain, raising new questions as to how Putin will respond, as well as how the alliance will navigate a new era for European security.


Graham Vyse: Finland and Sweden went through the Cold War, and the decades since, without joining NATO. Why is that?

Susan Colbourn: When NATO was formed in 1949, in the early years of the Cold War, it was designed by the United States, Canada, and Western European leaders, from the perspective of how they saw the threat posed by the Soviet Union. At that time, it had been a decade since Finland had fought the Winter War against the Soviets—who invaded their country three months after the outbreak of World War II—and managed to avoid being entirely taken over. But the Soviet Union forced Finland to sign a treaty promising to adhere to a policy of military neutrality. As a result, throughout the Cold War, Western leaders and analysts would refer to “Finlandization” as a distinctive brand of neutrality—and a warning of what the Soviets might hope to achieve elsewhere in Europe.

Sweden’s non-alignment stance dates back all the way to the early 19th century. The last war Sweden fought was in 1814, part of the many coalitions against Napoleon Bonaparte. At various points, officials within NATO discussed the possibility of Sweden joining, but these talks never really went anywhere. Geography helps explain it: If Sweden had opted to join NATO in 1949, it would have given the Soviets an excuse to exert even greater pressure on Finland, which was already neutralized by its treaty. And so, from the vantage point of Swedish security, NATO membership might not have made things more stable or secure.

Philip Myrtorp

Non-alignment really became embedded in Swedish identity, so we’re talking about decades, if not centuries, of foreign-policy traditions being changed right now. Now, despite their long-standing traditions of non-alignment, Finland and Sweden have both been actively working with—and had close ties to—NATO. The two countries joined the Partnership for Peace in the 1990s, using it as a way to deepen cooperation with the alliance. And that relationship deepened after Russia first initiated its war against Ukraine in 2014. Sweden and Finland both, for instance, already signed host-nation support agreements—agreements that would make it easier for the two countries to host NATO forces, if necessary.

On the one hand, Sweden and Finland applying for membership in NATO is a huge shift from old patterns in foreign policy. But on the other, it’s also not so surprising; it’s entirely consistent with the direction of their relationship with the alliance over recent decades.

Vyse: With Russia’s invasion of Ukraine being the immediate reason why these countries are finally joining NATO, how do you understand their decisions overall?

Colbourn: The attack on Ukraine fundamentally changed the security situation across Europe, including how the leaders of Finland and Sweden think about their own security. In press conferences over the past few days, officials from both countries described a sea change: They believe non-alignment may have served them well in the past, but they need to be part of NATO going forward. It’s all quite predictable, though it’s been striking how much Finland and Sweden have been working together toward membership. The thinking is that it may be harder for Russia to put pressure on them if they’re working together closely. These are two countries with very different domestic political landscapes and foreign policy traditions, yet they’ve been coordinated on this issue. It shows how seriously they’re taking it.

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