In full NATO membership, Prime Minister Sanna Marin announced this week that she has broad support in Parliament to install high metal fences on 10 to 20% of her border of nearly 1,300 kilometers with Russia, a construction site several hundred million euros.
Currently - and even during the time of the USSR - Finland has only meager existing wooden fences, mainly designed to prevent livestock from crossing the boundary.
Helsinki now wants to build higher barriers, made of a solid mesh and topped with barbed wire running along a road. Officially to protect themselves from a scenario of migratory influx, as on the border between Belarus and the European Union last year.
"I hope the construction can start as soon as possible," said Sanna Marin.
From Poland to Estonia via Latvia, several other countries of the European Union have already strengthened or plan to strengthen their land border with Russia.
The Finnish border guards have deemed it "necessary" to erect between 130 and 260 kilometers of fence in areas deemed crucial, especially in the south-east of the country which concentrates most of the border crossings.
Since President Vladimir Putin's order to mobilize for war in Ukraine in September, Finland has seen an influx of Russian citizens, until the country decided to crack down and drastically restrict entry.
The project, estimated at "several hundred million euros", will first be started on a few kilometers of pilot zone before the barrier is completely erected within three or four years.
The fence will not cover the entire border, which is largely in forested land and away from populated areas.
But according to border guards, it will help detect large groups and concentrate intrusions to smaller, more manageable areas.
Although the government is politically supported in its project, some experts doubt the objectives of such a construction.
"I think this barrier is an emotional reaction to the war," Olga Davydova-Minguet, an expert on Russia and border issues, told AFP.
It "reinforces the image of the Russian as a worrying source of threats" and the "sensation of danger beyond the border from which we must keep a distance".
- Porous border -
Symbolic delimitation between East and West, the Finnish-Russian border has so far been "a very pragmatic and practical border", explains to AFP Jussi Laine, professor of human geography at the University of Eastern Finland.
“Some children were able to go to school on the Finnish side while having parents living on the other side of the border,” he continues.
Subjected to forced neutrality by Moscow after their confrontation during the Second World War, Finland went through the Cold War with the tacit objective of not angering its powerful neighbour.
Since the 1990s and the end of the USSR, projects to develop electronic visas and new rail links had pushed to make the Russian-Finnish border a "normal border of Europe".
"In people's daily life, this meant that the relevance of a border would disappear", explains Jussi Laine.
Finland had also in recent years placed itself as a mediator in relations between the West and Russia.
But as with NATO membership, the situation changed radically with the war in Ukraine.
Before the invasion, in November 2021, an initial proposal by the center-right opposition to build a real barrier had been rejected, considered populist.
In July, five months after the start of the war, the Nordic country had already amended its law to allow the project.
Originally designed to respond to the "hybrid" threat of an organized migration crisis, the latter has evolved into an expression of condemnation of Russia, several analysts point out.
"This barrier has a symbolic value. It is not based on a rational analysis", estimates Jussie Laine, who worries about its perverse effects.
According to him, if the work of border guards could be made easier, the experience will "clearly show" that making it more difficult to cross borders fuels human trafficking.