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 European Union 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 European Union’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 K.G.B., opens or closes roads in a heavily militarized border region crammed with bases.