Fences have risen around kindergartens. Special vehicles transport military personnel to their work sites. Residents of the island settlement are afraid to leave their homes.

Novaya Zemlya is a Russian archipelago stretching into the Arctic Ocean. It once played host to Soviet nuclear tests, including the largest-ever man-made explosion, when the so-called King of Bombs detonated in 1961, releasing 50 megatons of power and deepening an arms race that threatened to turn the Cold War hot.

Today, the barren landscape is under siege — from dozens of polar bears locked in their very own sort of hot war. Marine ecologists have long been sounding the alarm about the peril posed by global warming for the vulnerable species.

Officials in the Arkhangelsk region, where the archipelago lies, on Saturday declared a state of emergency because of the marauding mammals. Polar bears are typically born on land but live mostly on sea ice, where they hunt and feed on seals. But as arctic ice thins, which is linked to the acceleration of climate change, the animals move ashore, ravenous. They scavenge, sometimes coming into contact with human populations.

Now, they could be selectively slaughtered if Russian authorities can’t figure out another way to keep them from menacing the residents.

TASS reported that the animals have tried to enter office buildings and residential quarters, and that they had chased residents and engaged in other aggressive behavior.

“The people are scared,” regional officials said in a statement. “They are frightened to leave homes and their daily routines are broken. Parents are afraid to let the children go to school.”

Residents are barred from hunting the animals.