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How the addition of Finland and Sweden would change NATO

Reservists of the Karelia Brigade fire live rounds during the Etel'-Karjala 22 (South Karelia 22) local defense exercise on March 9, 2022, in Taipalsaari, Finland. (Lauri Heino/AP)
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Early Thursday, Finland’s president and prime minister made an announcement as significant as it was expected: Helsinki would seek to join NATO as soon as possible.

The prompt for the decision decades after the trans-Atlantic security alliance was formed is obvious. Russia’s invasion of Ukraine earlier this year was a reminder to Finland that its eastern neighbor could not be trusted to respect their shared border. Not that Finland necessarily needed such a reminder; the then-Soviet Union invaded Finland about 80 years ago. But that was before Russia had nuclear weapons that it has repeatedly expressed a willingness to use.

So what does this mean? How does the probable addition of Finland — and the likely subsequent addition of Sweden — reshape the power balance between Russia and NATO? It’s likely that the alliance itself won’t change much, but the tension between NATO and its geopolitical opponent might.

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The most important issue is the Finland-Russia border itself. The expansion of NATO over time has been toward Russia’s western edge, with the collapse of the Soviet Union 30 years ago prompting a number of former Soviet states and Warsaw Pact countries to seek and gain membership in the alliance. On the map below (illustrated as though one was looking down at the North Pole), you can see how NATO expanded toward Russia. You can also see why Ukraine explored NATO membership for so long.

Some of Russia’s defenses of its incursion into Ukraine suggest that it was out of concern about having NATO on its border; a shoddy defense given that Russia already shared a border both with former Soviet states Estonia and Latvia and with a remote part of Norway. The addition of Finland, however, would extend the shared NATO-Russia boundary from about 440 miles to more than 1,200.

This doesn’t inherently make war more likely, but Finland’s shift to the West is the sort of change that Russia’s been hoping to prevent. In a statement, Russia’s government pledged to “take retaliatory steps, both of a military-technical and other nature, to stop the threats to its national security that arise in this regard.”

What NATO offers Finland is clear: security from its aggressive eastern neighbor. Curious what the addition of Finland and Sweden adds to NATO, I pulled data to see.

NATO is not contiguous, so land area is not a particularly useful metric, but aggregating the size of NATO countries relative to Russia is instructive. Russia is huge. With Finland and Sweden, the size of NATO countries is only 1.4 times the size of Russia in its entirety.

But much of Russia is unpopulated. The NATO countries have about six-and-a-half times the population of Russia. The addition of Finland and Sweden, however, wouldn’t change that much.

Where things get skewed quickly is on economics. The current countries of NATO had a 2020 gross domestic product equivalent to 27 times that of Russia — largely a function of the United States. Adding Finland and Sweden increases that to 27.6 times Russia’s GDP.

And then there’s military spending. One of the requirements of NATO membership is that nations spend a certain percentage of GDP on their military. (This was the metric that former president Donald Trump made a focus of his criticisms of NATO.) The current members of NATO spend about 24.5 times as much on their militaries as does Russia. (Iceland is an exception; it does not have a military but is a NATO member given its strategic location.)

Much of that spending is on material and technology. When considering the size of the standing military for each country, the ratio is smaller. NATO has about 3.2 times as many members of its collective militaries as does Russia — or as Russia did before its fumbling incursion into Ukraine.

Include military reserves and the margin narrows further: NATO has 1.7 times the military as Russia. But if we include Finland and Sweden here, the scale doubles. Finland, it turns out, has a massive military reserve.

Why? Largely because it shares that extensive border with Russia. After Russia annexed Crimea in 2014 and began engaging in military conflict in eastern Ukraine, Finland sent out renewed instructions to its large force of reservists. Again, Finland has a history of suffering from aggression from its east.

Now, seeing that aggression deployed nearby, Finland is seeking reinforcement from the West.