With Sweden and Finland, NATO wouldn't just get bigger. The alliance would also get a firepower boost

• Sweden and Finland are moving to join the NATO alliance.
• The move is a major rebuke of Russian President Vladimir Putin, who attacked Ukraine in part over concerns of NATO expansion.
• These two countries will be able to provide NATO with valuable military assets, including in the intelligence domain. 

Sweden and Finland are moving to join NATO, ending decades of neutrality, expanding NATO's border with Russia, and giving the organization a boost in combat power. 

The move toward the alliance by Sweden and Finland can be seen as a major rebuke of Russian President Vladimir Putin, who sent troops to Ukraine in February, purportedly in part due to concerns about the expansion of the NATO alliance.

The addition of Sweden and Finland to NATO would bring a lot to the alliance militarily – in the air, on land, at sea, and in the intelligence domain – according to Jim Townsend, a former Pentagon and NATO official.

For instance, Finland has one of the more powerful air forces in Europe, Townsend told Insider.

"They've been flying the F/A-18 with the latest US munitions hung on them, and they're going to buy the F-35," he said, referring to the US-made fifth-generation stealth fighter the country intends to acquire in a multi-billion deal.

And Sweden has in its arsenal of combat aircraft the Gripen fighters, a jet that the country previously claimed would excel at taking out Sukhoi aircraft. The Sukhoi aircraft flown by the Russians are notorious for their ability to maneuver in dogfights, but Sweden has said its jets have the edge.

"Gripen, especially the E-model, is designed to kill Sukhois. There we have a black belt," Maj. Gen. Mats Helgesson, then the commander of Sweden's air force, told Yle at a presentation in 2019. In particular, these planes are said to shine in electronic warfare.

On the ground, Finland has one of the strongest artillery forces in Europe with around 1500 different artillery systems. It also maintains relatively large and effective conscript and reserve forces. In December 2021 poll, 90% of male Finnish participants and 84% of women said they would be ready to defend their country to the best of their abilities, some of the highest figures in Europe.

And, "when it comes to fighting in the Arctic and fighting in the snow, nobody beats the Finns," Townsend said, commenting on the capable nature of Finland's modern land forces, as well as the country's historic combat prowess in winter warfighting.

He added that both Sweden and Finland have "very professional and modern" navies, explaining that "they carry, in terms of sensors and shooters, quite an interoperable and capable mix of firepower." Swedish subs, for example, have demonstrated their effectiveness in naval war games.

In a 2005 exercise, Sweden's HSMS Gotland, a small diesel-powered submarine with a quiet, Stirling engine, was able to get close to and take out the USS Ronald Reagan, a $6.2 billion US Navy aircraft carrier, without detection. Over the next few years during war games, the Gotland was continuously successful, able to stealthily overcome destroyers and nuclear attack submarines.  

Finland, which shares a border with Russia, would also bring to NATO additional intelligence that could prove critical in a conflict scenario.

"NATO doesn't have its own active intelligence capability – they depend on allies bringing intelligence to NATO, so Finland would play a big role there," Townsend said. "They do watch the Russians carefully," he said, adding that "they're more familiar than many allies are with Russia."

Amid the ongoing fighting in Ukraine, which has triggered an increased interest in NATO, Finnish Prime Minister Sanna Marin and President Sauli Niinisto confirmed on Sunday that the country would apply for NATO membership. "This is a historic day. A new era begins," Niinisto told reporters, according to the Associated Press.

And on Monday, Swedish Prime Minister Magdalena Andersson also confirmed the country's desire to join NATO.

"There is a broad majority in Sweden's parliament for Sweden to join NATO," Andersson said. "This is the best thing for Sweden's security."