Russia invaded Finland without provocation early on....after having invaded Poland without provocation in 1939. Russia also invaded Hungary in 1956 and Czechoslovakia in 1968....again, without actually needing to defend their borders.Russia has the same right to defend its borders from hostile military forces as the US has to impose its Monroe Doctrine. Finland offers a recent example of neutrality:
http://nato.gov.si/eng/topic/national-security/neutral-status/neutral-countries/#:~:text=Finland derives its policy of,, Cooperation and Mutual Assistance).
"Finland derives its policy of neutrality from the period directly following the Second World War.
"Its interest in remaining neutral in conflicts between great powers was first recognised in a treaty between Finland and the USSR in 1948 (the Treaty of Friendship, Cooperation and Mutual Assistance).
"The treaty forbids the signatories to join a military alliance against the other, and Finland could not allow its territory to be used for an attack on the USSR.
"Finland was also bound to preserve its neutrality through adequate armed forces.
"Finland's neutrality does not have roots in international law, and there are no international pledges for its neutrality.
"Thus Finland, like Austria, is a case of enforced neutrality, again by the USSR."
Seems to have repeated history. So Stalin imposed neutrality on Finland by threat of an additional invasion after the end of the war. You seem to think that can be classified as "defending its borders". It isn't.