KANDALAKSHA, Russia >> So many decrepit Soviet-era cars carried migrants into Europe from this frozen Russian town in recent months that border officials in Finland, who confiscate the rust-bucket vehicles as soon as they cross the frontier, watched in dismay as their parking lot turned into a scrapyard.

To clear up the mess and provide some space for freshly confiscated cars, the Finnish customs service set up a separate dumping ground.

Then last month, as suddenly and as mysteriously as it had started, the parade of migrants in rusty old cars came to an abrupt halt, or at least a pause.

“We don’t know what is going on,” said Matti Daavittila, the head of the ice-entombed Finnish border post near Salla. “They suddenly stopped coming. That is all we know.”

Compared with the hundreds of thousands of people fleeing war or hardship who made the trek to Europe last year through Turkey to Greece, the flow of refugees and migrants on the Arctic route through Russia — first into Norway and later into Finland — is tiny.

But the stop-go traffic has added a hefty dose of geopolitical anxiety, not to mention intrigue, to a crisis that is tearing the European Union apart.

It has sent alarm bells ringing in Helsinki, Finland’s capital far to the south, and in Brussels, where EU leaders, at recent crisis meetings on migration, discussed the strange and ever-shifting Arctic route through Russia.

The intrigue flows from a growing suspicion in the West that Russia is stoking and exploiting Europe’s migrant crisis to extract concessions, or perhaps crack the European unity over economic sanctions imposed against Moscow for its actions in Ukraine. Only one of the EU’s 28 member states needs to break ranks for a regime of credit and other restrictions to collapse.

“Unfortunately, this looks like a political demonstration by Russia,” said Ilkka Kanerva, Finland’s former foreign minister and now the chairman of its parliamentary Defense Committee. “They are very skillful at sending signals. They want to show that Finland should be very careful when it makes its own decisions on things like military exercises, our partnership with NATO and European Union sanctions” against Russia.

Unlike the flow of refugees and migrants into Greece by boat, in which the tempo is largely set by the weather in the Aegean Sea, the flow through Russia is almost entirely dependent on whether Russia’s Federal Security Service, the successor agency to the KGB, opens or closes roads in a heavily militarized border region crammed with bases.

In the first two months of this year, nearly 800 asylum seekers crossed from Russia into Finland near Salla, a crossing point west of Kandalaksha in the Finnish region of Lapland, compared with none in same period last year.

Jorma Vuorio, the director general of Finland’s Migration Department, said he had been surprised by the “completely new phenomenon” of asylum seekers arriving from Russia. But he added that there “was no proof, just speculation,” of involvement by the Russian state.

The traffic into Europe through the Arctic, which has involved relatively few Syrians, began late last summer, with more than 5,000 migrants on bicycles suddenly pouring across Russia’s previously tightly controlled northern border into Norway. But that cycle-borne flow ended abruptly on Nov. 30, after the Russian authorities reintroduced tight controls just as Norwegian officials arrived in Moscow for talks on how to stem the flow.

The migrants’ route then shifted southward to Russia’s border with Finland, as Russian guards on roads to two Finnish border crossings stopped blocking travelers without visas.

Finland swiftly banned cycle traffic across its 830-mile border with Russia, allowing only people in cars to cross. This killed a booming market for old bicycles in Russia’s far north but created a new market for cheap and decrepit Russian cars with just enough life left in them to limp across the border to Finland.

Vuorio said his Russian counterpart had informed him that Russia had more than 11 million foreigners living in its territory, a vast pool of potential migrants to Europe, but added that he doubted Moscow would allow a chaotic flood through sensitive border regions. Criminal gangs, not officials, he added, seem to be largely responsible for managing the scale and direction of migration to Europe through Russia.

He said the last halt in the traffic was not the result of any deal struck by Finnish and Russian officials, who have been engaged in weeks of intensive, high-level discussions. “Our only deal is that we have good relations,” he said, bewildered by the stop-go flow.

But that, said the Defense Committee chairman, Kanerva, is precisely Russia’s aim — to keep Finland off balance and thus wary of making any move toward NATO or making other decisions that would anger Moscow. Noting that Russia had shown itself adept in Ukraine at so-called hybrid warfare, the use of nonmilitary tools to pursue its goals, he said migrants “are part of a broader strategy.”

“They want to make us nervous and pay attention to their interests,” he added.

The one group that needs no convincing about Russia’s manipulation of the migrant issue is the migrants themselves.

In interviews in Kandalaksha, stranded migrants from West and Central Africa said they had each paid thousands of dollars to “guides” who promised to get them to Finland and who worked closely with Russian officials. The system was highly organized, the migrants said, with no more than 30 people allowed to make the journey to Finland each day. Who went when, and in which vehicle, was established in advance, they said, with the guides and officials drawing up detailed lists with names, departure dates and cars.

“They are all in the same clique: the officials, the hotel people, the drivers. This is their business,” said Honoré Basubte, a young migrant from West Africa who had come to Russia as a student. Like many of the other migrants who traveled to Kandalaksha, he said he had been issued a Russian deportation order before setting out and been told to leave quickly for Europe.

“Now they say we can’t go because the border is closed,” he said. “This is all an ugly game.”

© 2016 The New York Times Company