Well maybe because the Polar ice is melting the Russians have started bringing their nuclear subs to the surface and they feed the Polar bears Capitalist food like minute rice and pop tarts. And when the Russians feed the bears they use sweet talk so the bears lose their fear of humans. After the Russians leave the bears start to crave capitalist food and sweet talk so they wonder into towns and villages. Then when everybody is busy running around because their afraid the polar bears are going to eat them the Russians will attack. Cheers!