What Would Happen If Russia Invaded Finland? Experts Weigh In

The Nordic nations of Finland and Sweden will consider applying to join the NATO military alliance despite warnings from Russia that the countries should not change their current status.

Finnish Prime Minister Sanna Marin said her country will hold a debate on the matter and make a decision shortly afterwards, while Swedish Prime Minister Magdalena Andersson joined Marin at a press conference in Stockholm on Wednesday and said her country was also considering applying for NATO membership.

Both countries have a long and often difficult history with Russia, marked by war and mutual distrust. The decisions to consider NATO membership appear to be prompted by Russia's ongoing invasion of Ukraine, which began on February 24 and has seen around 11 million Ukrainians flee their homes.

Former Russian president Dmitry Medvedev warned on Telegram on Thursday that if Sweden and Finland join the military alliance, his country could deploy nuclear weapons to the Baltic.

Russian Soldiers Patrol Mariupol in Ukraine
Russian soldiers patrol Mariupol in Ukraine on April 12, 2022. Russia has warned Finland and Sweden against joining NATO. ALEXANDER NEMENOV/AFP/Getty Images

"If Sweden and Finland join NATO, the length of the land borders of the alliance with the Russian Federation will more than double. Naturally, these borders will have to be strengthened," said Medvedev, who is currently deputy chairman of the Russian Security Council.

Russian threats may be of particular concern to Helsinki, which shares a border with Russia that is more than 800 miles long. Finland has been invaded by Russian or Soviet forces three times since 1918.

Experts who spoke to Newsweek suggested that a Russian attack on Finland would not go particularly well for Moscow, citing the country's recent difficulties in Ukraine.

Tapped Out

Dr. Stephen Biddle is an adjunct senior fellow for defense policy at the Council on Foreign Relations. He told Newsweek that a Russian invasion of Finland would not be an easy matter.

"Russia is now very nearly tapped out for combat maneuver forces as a result of their operations in Ukraine," Biddle said.

"They don't have a lot left for a major offensive in Finland, and anything they commit to Finland detracts from their ability to prosecute the war in Ukraine," he said.

"The Finns' military isn't huge, but it isn't tiny either, and is much better trained and motivated than the Russians," Biddle added.

Striking Finland

Though Russia's military operations in Ukraine may mean it cannot commit forces to an invasion, Biddle suggested Russia could take some form of action.

"I could imagine Russia striking Finland with missiles, artillery or air strikes as a way to create a conflict that would make NATO wary of admitting Finland, but I think it's very unlikely that Russia could simply conquer Finland given all this," he said.

"And I suspect the Russian General Staff is wary of starting another war that could easily become another stalemated quagmire on top of the one they could be facing in Ukraine," Biddle added.

A History of Conflict

Dr. Ian Johnson is assistant professor of military history at the University of Notre Dame. He told Newsweek that Russian forces had not previously been able to conquer Finland.

"Russian or Soviet forces have launched three major invasions of Finland since 1918," Johnson said. "None of the conflicts resulted in outright military defeat for Finland, despite the vast disparities in the size and population of the two states."

Johnson explained that the Red Army invaded Finland during the Russian Civil War in 1918 but their opponents, the Finnish Whites, "eventually won in three months of fighting, drove the Russians out, and established the modern Republic of Finland."

In the Winter War of 1939-40, the USSR invaded Finland "with the aim of seizing several border regions, and, if possible, establishing a pro-Soviet puppet government."

"Soviet plans to occupy the whole country fell apart after crushing military defeats suffered in the first month of the war," Johnson said.

"But eventually, superior Soviet numbers began to overwhelm Finnish defenses. In March 1940, the Finnish government agreed to a peace treaty that gave Stalin what he had sought territorially, but left Finland independent," he said.

Huge Advantages

The two countries went to war again in 1941 when Finland attacked the USSR with the aim of regaining the lost territory. This occurred after Nazi Germany launched its own invasion of Josef Stalin's Soviet Union and Soviet air raids against Finnish cities, Johnson said.

"The Continuation War, as it became known, was marked by a rapid Finnish advance, followed by trench warfare that lasted until 1944," Johnson explained.

"In the end, Finnish forces inflicted heavy losses on the Soviets, but eventually sued for peace, once again ceding territory," he said.

Johnson noted that the two wars "cost Finland 15 percent of its national territory."

"But Finland avoided the fate of its Baltic neighbors, which were annexed by the USSR and suffered heavily at the hands of Soviet secret police," he said.

"In the Winter War and the Continuation War, the Soviets suffered roughly six casualties for every Finnish casualty, despite huge advantages in equipment and manpower," Johnson said.

"High Finnish morale, effective leadership, the use of encirclement, and effective defense of the country's heavily wooded terrain were the major reasons behind the successes of Finnish forces," he went on.

If history is any guide, a Russian invasion of Finland would be difficult and potentially costly for the invaders. The ongoing invasion of Ukraine may also serve as an example not unlike previous Finno-Russian conflicts.

Military Reserves and Western Weapons

Johnson told Newsweek that while Finland had been forced to "demobilize much of its military" when peace negotiations with the USSR ended in 1947, the country was allowed to have military reserves.

"As a result, Finland has maintained near-universal conscription, with a large active reserve force," Johnson said.

"Although its full-time professional military numbers only 22,000 active personnel, roughly 900,000 Finns constitute the country's reserve forces," he went on.

"And unlike Ukraine, these forces are armed primarily with western European and American weapons systems, including the German-made Leopard tank and U.S.-made F-18 Hornet fighter," Johnson explained.

"The Russian armed forces are very fully engaged in Ukraine, and already suffering manpower and logistical shortages," he went on.

"But in the unlikely event Russia should attempt military action against Finland in the near-term, both history and the realities of Finnish military preparations suggest that it would not go well," Johnson said.

NATO and Russia's Failure

Dr. Patrick Bury is associate professor in security at the University of Bath in the U.K. He served in the British army as an air assault infantry captain and later worked as an analyst for NATO. Bury told Newsweek he expected Finland and Sweden would be accepted into NATO quickly.

"Both are NATO Partnership for Peace members already, so will have an understanding of NATO organization and standards," Bury said.

"Sweden in particular, with its comparatively large and capable defense forces, was viewed as a valuable contributor when I was at NATO," he said.

"In the event of a formal application to join, I'd expect NATO to accept both countries quickly, proving another Russian failure to fully understand the implications of its invasion."

Bury also pointed out that Finland joining the alliance would increase NATO's border with Russia "by 830 miles—a not insignificant area when the alliance is currently rethinking its force posture on its eastern flank."

Newsweek has asked the Finnish Ministry of Defense for comment.