HELSINKI (AP) — Finland said Tuesday it will close its last remaining border crossing with Russia amid concerns that Moscow is using migrants as part of “hybrid warfare” to destabilize the Nordic country following its entry into NATO.

Finland already had shut seven of the eight checkpoints on its 1,340-kilometer (830-mile) border with Russia this month following a surge in arrivals of migrants from the Middle East and Africa. Helsinki has accused Moscow of ushering them toward the frontier — through thick forests in the south to the rugged Arctic landscape in the north.

“The government has decided to close all the crossing points on the entire eastern border,” Prime Minister Petteri Orpo told reporters, saying Finland faced an “exceptional” situation that the government blames on Moscow for orchestrating.

“Finland has a profound reason to suspect that the entry (of migrants) is organized by a foreign state. This deals with Russia’s influencing operations and we won’t accept it," Orpo said bluntly. "We don’t accept any attempt to undermine our national security. Russia has caused this situation and it can also stop it.”

The complete closure announced Tuesday is due to last for at least two weeks, after which one crossing point may be reopened, the Finnish government said.

The current situation means migrants arriving from Russia only would be able to seek asylum upon arriving at Finnish airports or harbors. However, there is currently no air or passenger boat traffic between Russia and Finland, so those options don't exist.

The Kremlin denies encouraging migrants to enter Finland and says it regrets the Finnish border closures. Russian Foreign Ministry spokeswoman Maria Zakharova argued last week that Helsinki should have instead tried to “to work out a mutually acceptable solution or receive explanation.”

Finnish authorities say some 1,000 migrants without visas or valid documentation have arrived since August at the normally heavily controlled border, which makes up a significant part of NATO’s northeastern flank and acts as the European Union’s external border in the north.

Of that number, about 900 of those coming to Finland's border with Russia arrived this month, an unusual increase for the country of 5.6 million, the Finnish authorities said. The asylum-seekers are from countries that include Eritrea, Ethiopia, Iraq, Pakistan, Somalia, Syria and Yemen, they said.

Most are young men in their 20s and 30s, but some are families with children and women, border guard data and photos indicate. Many of them were dressed in sneakers and light outdoor gear. Nearly all arrived at the border zone on bicycles that Finnish and Russian media reports say were provided and sold to them.

The governor of Russia’s northern Murmansk region last week said there were at least 400 people waiting to enter Finland on the Russian side of the border and that the number was expected to increase as Helsinki closed its crossing points bit by bit.

Orpo said in a separate statement that Russia was guiding people to the border "in harsh winter conditions. Finland is determined to put an end to this phenomenon.”

Two years ago, the EU accused Russia's ally Belarus of using migrants seeking a better life in Europe as pawns to destabilize Western democracies. European leaders called it a form of “hybrid warfare” by Moscow, along with disinformation, election interference and cyber attacks.

Finnish Foreign Minister Elina Valtonen used that same term in a Nov. 22 interview with The Associated Press.

She said there is no doubt that Russia “is instrumentalizing migrants” as part of its “hybrid warfare.” Before joining NATO this year, a decision prompted by Moscow’s invasion of Ukraine, Finnish officials warned that Russia could seek ways to destabilize the country in retaliation, including cyber attacks and ushering migrants to its borders -- something that happened in Finland during the winter of 2015-16.

“We have proof showing that, unlike before, not only Russian border authorities are letting people without proper documentation to the Finnish border, but they are also actively helping them to the border zone,” Valtonen said.

Some Western political analysts believe Russia’s motive is to create havoc on the EU’s external borders.

For decades, Finnish and Russian border authorities both checked that only people with proper documents can cross -- both ways. Recently, however, Finnish officials noted the change in checks by Russian guards, who normally don't allow foreigners to within a radius of several kilometers (miles).

Interior Minister Mari Rantanen said the last border crossing for vehicle traffic that remains open, Raja-Jooseppi in Finland's Arctic north, would close at midnight Wednesday and stay shut until Dec. 13. A rail crossing between the two countries remains open but only for cargo traffic.

___

Follow AP's coverage of global migration at https://apnews.com/hub/migration