Finland has a close history with its largest next-door neighbor. Perhaps too close. “Finland was a province and then a grand duchy under Sweden from the 12th to the 19th centuries, and an autonomous grand duchy of Russia after 1809. Finland gained complete independence in 1917″ from Russia after the World War I.  Recent events could have Finland joining NATO due to fear of the Russian bear.
In November 1939, the Red Army of the Soviet Union invaded Finland with half a million men.The Soviets expected the small nation to quickly capitulate, however, the Finns resisted. Much of the fighting took place in the forests of Finland, with the Finns moving about on skis and bicycles. However, by March 1940, the Finnish resistance was degraded due to the overwhelming material and personnel advantage of the Soviets. The Finns would be forced to cede the Karelian Isthmus to the Soviets. 
Many defense analysts believe that Finland joining NATO would ensure that country’s security from aggressive Russian actions. In fact, in late June 2016, the Finnish government said that it was exploring the benefits of NATO membership. However, there could be repercussions. This would essentially put NATO (the Finn military) right on the Russian border. Russia has said that it could be forced to reinforce its northern border with Finland should the Finns join NATO.  Finland is also increasing its defense spending; currently it ranks only 62nd in the world, spending just 1.35 percent of its gross national product. 
Finland has been cooperating with NATO on a variety of levels. It participates in the NATO Resolute Support Mission in Afghanistan, supplying small units to the northern region of Afghanistan and individuals to the Resolute Support headquarters in Kabul. Finland also belongs to the NATO Partnership for Peace program (since 1994).
One possibility is for Finland to not join NATO, but to establish a bilateral agreement with the United States.  The lack of cohesion within NATO has Finland and the Baltic region concerned.
Finland has a lot of experience with this delicate balancing act, seeking to get itself out from under Soviet Union and, later, Russian dominance, yet not antagonizing the Russians to the extent the Russians take economic, diplomatic, or military action. The situation can go either way; it is up to the Russians to decide how aggressive they want to be. So the Russians have their own balancing act to perform. At some point, Finland joining NATO could be a future event.
 CIA World Factbook – Finland, page 12.
 A legendary figure in the history of U.S. Army Special Forces is Larry Thorne – a Finn who fought the Russians in The Winter War, then as a member of the German Army fighting the Russians during World War II, and finally after joining the Green Berets fighting in the Vietnam War.
 see “Putin Hints at Troop Movements if Finland Joins NATO”, Radio Free Europe / Radio Liberty, July 1, 2016.
 CIA World Factbook – Military Expenditures by Country.
 See “Sweden and Finland upgrade NATO relations”, EU Observer, May 20, 2016.
WikipediA, Winter War.
NATO, Relations with Finland, North Atlantic Treaty Organization, June 14, 2016.
Ministry for Foreign Affairs of Finland, Mission of Finland to NATO.