A Russian police officer patrols Red Square in the bitter cold of Russian winter. Because Russia lacks geographic barriers to prevent invasion, the relatively inhospitable climate has often served as the country's best defense.
Russia's defining characteristic is its indefensibility. Unlike the core of most states that are relatively defensible, core Russia is limited to the region of the medieval Grand Principality of Muscovy. It counts no rivers, oceans, swamps or mountains marking its borders — it relies solely on the relatively inhospitable climate and its forests for defense. Russian history is a chronicle of the agony of surviving invasion after invasion. Traditionally these invasions have come from two directions. The first is from the steppes — wide open grasslands that connect Russia to Central Asia and beyond — the path that the Mongols used. The second is from the North European Plain, which brought to Russia everything from the Teutonic Knights to the Nazi war machine. To deal with these vulnerabilities, Russia expanded in three phases.
