IMATRA, Finland (AP) — The construction of barbed-wired fence along Finland’s long border with Russia - primarily meant to curb illegal migration - has broken ground near the southeastern town of Imatra less than two weeks after the Nordic country joined NATO as the 31st member of the military alliance.

The Finnish Border Guard on Friday showcased the building of the initial three kilometer (1.8 mile) stretch of the fence to be erected in Pelkola near a crossing point off Imatra, a quiet lakeside town of some 25,000 people.

Finland’s 1,340 kilometer (832 mile) border with Russia is the longest of any European Union member.

Construction of the border fence is an initiative by the border guard that was approved by Prime Minister Sanna Marin's government amid wide political support last year. The main purpose of the three-meter (10-foot) high steel fence with a barbed-wire extension on top is to prevent illegal immigration from Russia and give reaction time to authorities, Finnish border officials say.

In 2015-2016, Moscow attempted to influence Finland by organizing large numbers of asylum-seekers to northern Finnish crossing points in the Arctic Lapland region. Russian authorities were seen deliberately ushering thousands of asylum-seekers - mostly from Iraq, Afghanistan and other Middle East nations - to those border crossing points.

This is a scenario that Finland - a nation 5.5 million people that officially became a NATO member on April 4 - wants to prevent from repeating itself.

Border officials are quick to acknowledge, however, that it was Russia’s invasion of Ukraine on Feb. 24 last year - the main reason for Finland’s quick push to join NATO after decades of military nonalignment - that prompted construction of the border fence.

“Border barrier fence was no kind of political topic before the war (in Ukraine). And actually, it wasn't a kind of plan of the Finnish border guard,” Brig. Gen. Jari Tolppanen, head of the technical division at the Finnish Border Guard, told The Associated Press. “All changed after the attack (of Russia against Ukraine).”

The pilot section of the fence is scheduled to be completed by this summer, while the barrier will eventually be extended to a maximum of 200 kilometers (124 miles). It will cover areas - in bits and pieces of separate length - mainly in southeastern Finland near the main border crossing points with Russia but it will also have sections up in the Arctic north in Lapland.

“In this new situation, we must have much more credible and much more independent border control,” Tolppanen said. “We need to strengthen our resources. And the fence is necessary in order to manage, for example, large-scale illegal immigration.”

Imatra is located a mere seven kilometers (4.4 miles) off the Russian industrial town of Svetogorsk in the Karelia region and is a few hours’ drive away from Russia’s second city of St. Petersburg. The town has a long history in dealing with Russians - tourists, day-trippers and permanent residents alike.

“Here in Imatra, we’re not so afraid about Russians because the border has always been there and it has never been open like between European countries,” said Antero Lattu, vice chairman of Imatra City Council. He stressed that locals aren’t afraid of Russians “but we're happy because of that fence."

Erkki Jouhki, who works as a town planner, agreed but also stressed Finland's military capabilities. NATO membership gives Finland “a strong back but we have a very strong army. it’s very well (armed) ... it’s a very modern army here because of Russia.”

The border fence project is estimated to cost a total of 380 million euros ($422 million) and is scheduled to be completed by 2026.

Finland’s long eastern frontier runs mainly through thick forests. In some places the Finnish-Russian border is marked only by wooden posts with low fences meant to stop stray cattle.

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Jari Tanner in Helsinki contributed to this article.