Experts are speculating over Russia's next move. They may want to check Ukraine's weather forecast

Even in the 21st century, warfare is affected by weather -- and that may become a factor in any Russian offensive into Ukraine. The question on the lips of Ukrainians, and maybe Russian generals: "Has Rasputitsa come early?"

Rasputitsa is the term for the mud of spring, when travel in Russia and Ukraine by road becomes more difficult. Usually its impact is most felt in March, as the snows begin to melt.

So far, this winter has been unseasonably mild in much of Ukraine. As CNN drove from the eastern port city of Mariupol to Zaporizhzia in central Ukraine on February 1, it began to rain. The driver shrugged in disbelief. "Should be snow," he laughed.