In the two weeks since ambassadors from all NATO member states signed the accession protocols for Finland and Sweden to join the alliance, approximately half of the member countries have now ratified the decision. But as countries such as Hungary, Turkey, and the United States still have yet to ratify, it is worth taking stock of how the alliance would benefit from adding the two Nordic countries.

Finland and Sweden will bring two relatively small but advanced militaries into NATO, adding significant military capabilities and augmenting the alliance’s ability to deter additional Russian aggression. And contrary to suggestions by opponents of NATO enlargement, the addition of the two countries would strengthen transatlantic security and decrease the probability of Russian aggression against the alliance.

Consider some of the specific air, sea, and land capabilities Finland and Sweden will add to the alliance’s arsenal.

According to the International Institute for Strategic Studies’ Military Balance 2021 report, the two countries will collectively contribute over 150 fighter aircraft, including 96 JAS-39 Gripens and 62 F/A-18 Hornets. By the end of the decade, Finland intends to acquire 64 fifth-generation F-35 fighter aircraft. This compares with Polish plans to acquire 32 F-35s and Italian plans to acquire 90 F-35s.

Sweden is also set to procure two advanced GlobalEye airborne early warning and control (AEW&C) aircraft, more capable platforms than the aging E-3A AWACS planes NATO currently uses to monitor European airspace. AEW&C aircraft are critical components of an effective air defense system. Indeed, at their June 29 summit in Madrid, NATO members endorsed a strategy to “ensure the seamless delivery of the next generation Airborne Warning & Control System (AWACS) and related capabilities.”

Sweden also possesses a skilled navy with Visby-class corvettes and Gotland-class submarines. These would improve NATO’s ability to deter and defeat maritime aggression and protect sea lines of communication. Islands belonging to Sweden and Finland, especially Sweden’s Gotland Island in the middle of the Baltic Sea, will greatly complicate potential Russian naval operations.

Finland and Sweden would also bring significant land warfare capabilities to the alliance. Finland possesses one of the most capable artillery forces in Europe, with M270 Multiple Launch Rocket Systems and hundreds of towed howitzers. Finland has more artillery pieces than France, Germany or the United Kingdom. Together, Finland and Sweden boast 220 active Leopard main battle tanks, nearly matching Germany’s 245 Leopards, another meaningful contribution to deter an attack on NATO territory.

Sweden has also operated the Patriot air defense system since November 2021, while Finland operates NASAMS, the same system that protects Washington, DC. Additionally, both countries are considering buying Israeli-made air defense systems, which would further increase their contribution to the NATO alliance.

While NATO militaries have worked with their Finnish and Swedish counterparts for years, their membership in the alliance will allow these capabilities to be written into NATO war plans and deepen the level of integration. That will create additional dilemmas for Russian military planners, making aggression against the alliance less likely.

Some opposed to Finland’s and Sweden’s accession acknowledge their military contributions but suggest they would be outweighed by a new obligation to defend those countries against Russian aggression.

It is certainly true that NATO members would be expected to come to the aid of Finland and Sweden if they were attacked. After all, the heart of the NATO alliance is Article 5 of the North Atlantic Treaty, which states that “an armed attack against one or more of them in Europe or North America shall be considered an attack against them all.”

But that’s exactly the point.

It’s no coincidence that Russia has invaded and occupied Georgia and Ukraine (which are outside NATO) but has not dared invade a NATO member for more than seven decades. Putin appears to understand that an attack against a NATO member country would risk war with the United States. What’s more, by complicating Russian military planning, Finland and Sweden can strengthen NATO’s deterrence of Russian aggression against other members, too.

During times of relative peace and stability, non-Finnish NATO deployments in that country can and should be managed prudently to avoid unnecessary tension with Moscow. But if Moscow were to rattle its saber against NATO members in the Baltics or elsewhere, additional NATO forces could be moved into Finland.

Additional capabilities there would force Russian military planners to watch the 832-mile border and redirect finite combat forces to Moscow’s northwest. That would spread Russian forces more thinly across a wider front and make any scenario for potential aggression seem even less feasible to the Kremlin than it does now.

Strengthening NATO’s deterrent in this way might hasten the day when Russian leaders realize that the best path to peace and security is respecting the borders and sovereignty of its neighbors.

In the meantime, a careful review of Finland’s and Sweden’s military capabilities and the geo-strategic advantages associated with their addition to NATO makes clear that their accession would enhance the alliance’s deterrence of Russian aggression and serve transatlantic security interests.

That’s why the remaining NATO member countries should welcome Finland and Sweden into the alliance without delay.

Bradley Bowman serves as senior director of the Center on Military and Political Power at the Foundation for Defense of Democracies, where Ryan Brobst is a research analyst, Jack Sullivan is a research associate, and John Hardie is a senior research analyst. Ashlyn Cox contributed to this article.

More In Commentary