(Bloomberg) -- Sweden’s entry into NATO can help solve a critical problem for military planners mapping out the alliance’s defenses against a potential Russian attack: how to rapidly shuttle troops, weapons and other provisions to a front anywhere from the Baltic to the Arctic. 

After months of delays, the green light for Sweden’s membership means the Nordic nation can finally be woven into the North Atlantic Treaty Organization’s intricate defense plans, which designate Russia as a primary threat. 

The move is more pressing with Russian troops starting to advance in Ukraine again. With Russian President Vladimir Putin’s expansionist ambitions apparent, European officials have started warning about the prospect of an attack on NATO within the next few years.

“We know that our eastern neighbor is highly unpredictable and also unfortunately very aggressive,” Finnish Foreign Minister Elina Valtonen said in an interview. “But Sweden knows, and we also tell Sweden, that as members of NATO we are stronger together.” 

After decades of non-alignment, Sweden and Finland applied to join NATO within months of the Kremlin’s full-scale invasion of Ukraine in 2022, fearing they were vulnerable to Putin’s aggression. 

Finland became a member of the alliance in April, while Sweden was left in limbo by Turkey and Hungary. 

Budapest was the last of the 31 allies to back Sweden’s accession with the parliament signing off in late February, after the two nations sealed a deal to ship four additional Swedish Gripen fighter jets to Hungary.

Sweden’s membership was completed as remaining paperwork was submitted on Thursday. Its flag will be raised at NATO headquarters in Brussels on Monday.

In some ways, the move is simply a rubber stamp. After years of training with NATO allies and defense plans forged with its Nordic neighbors, Sweden is already well-integrated into the alliance. For most of the past two years, it also took part in almost all NATO meetings as a guest. 

“NATO membership is the logical continuation of the security policy that Sweden, in reality, has been following for many decades,” Prime Minister Ulf Kristersson told his nation in a speech Thursday. 

“Where Sweden would turn in case of war has never been in doubt,” he said. During the Cold War, “military cooperation was sensitive and often secret. Now, we can cooperate openly and honestly as allies.”

Becoming a full member removes any ambiguity about whether NATO would defend Sweden in the event of an attack, and vice-versa, said a senior alliance official with knowledge of NATO’s defense plans. That means Russia couldn’t persuade Sweden to look away or side in its favor, the official added.

Along with its strong navy and formidable air power, Sweden’s geography will play a crucial role in helping NATO deter any Russian attack — be it in the Baltics, along the Finnish border, or in the Arctic, officials say. 

Given the central part logistics play in sustaining a war, Sweden’s roads and railways are often the fastest routes to traverse the curving Scandinavian peninsula, including from one point in Norway to another in the same country.  

In the Baltic, long seen as NATO’s Achilles heel, Estonia, Latvia and Lithuania will be able to rely on more immediate help and new routes for supplies from Finland, but also now from Sweden. Sweden’s island of Gotland, often referred to as an unsinkable aircraft carrier, cements NATO’s position in the region, locking in control of critical naval routes and airspace.

With Sweden and Finland on board, the vulnerability of the Suwalki Gap is also lessened. That’s a stretch of land between the Russian exclave of Kaliningrad and its ally Belarus which Moscow could cut off in a conflict. Allies in the past would have needed to squeeze through the gap to reinforce the Baltic nations.

Sweden has already said it aims to bolster NATO presence in Latvia by sending troops to the Canadian-led forces there. There are no current plans to station alliance troops in Sweden, but the matter will be discussed, the senior NATO official said.

‘Perfect Fit’

The Nordic country is in the process of rebuilding its armed forces after decades of downsizing following the end of the Cold War, during which Sweden’s government freed up resources for other needs while also reducing debt to one of the lowest levels in Europe.

While Sweden will this year reach NATO’s goal to spend at least 2% of gross domestic product on defense, the history of underspending is displayed in part in its navy. The branch is viewed as a strong asset to allied forces but is small, with five submarines — plus two more due for delivery by the end of the decade — as well as five stealth corvettes and as many minesweepers. 

“We have the longest Baltic Sea coast and one of Europe’s longest coastlines so in relation to the environment we operate in, the navy is very small,” Navy chief Ewa Skoog Haslum said in an interview. 

But, she added, “we are one of few nations that are fully able to handle this environment, especially when it comes to the subsea dimension.”

Unlike allies’ submarines, Sweden’s are tailored to function in the shallow waters of the Baltic Sea and can play a significant role in monitoring undersea critical infrastructure, according to a recent report by the Atlantic Council. 

That’s a vital capability amid recent sabotage incidents on subsea systems, episodes that are likely to become more frequent. With Russia’s land forces bogged down in Ukraine, Moscow could turn more to such relatively cheap tactics to stir chaos among NATO allies. 

At a conference in Sweden last year, General Christopher Cavoli, NATO’s supreme allied commander for Europe, pointed to Sweden’s capabilities and other elements that will allow the nation to be compatible with allies from day one of joining.

“It should be a perfect fit, easy,” Cavoli said. “And it’s good if it’s easy, because I think the future looks hard.”

--With assistance from Christopher Jungstedt, Ellen Milligan, Jeremy Diamond and Gina Turner.

(Updates with comments from Sweden’s prime minister from 10th paragraph)

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