Source: The Wall Street Journal By George Weigel While Vladimir Putin is determined to reconstitute the old Soviet Union as a sphere of unchallenged Russian influence, Russian imperialism has a history that long antedates Mr. Putin. Czarist Russia was an expansive imperial power, extending its hegemony over the Eurasian landmass to the Pacific Ocean. Lenin, Stalin and their epigones, despite their ideological rejection of czarism, acted as de facto Great Russian imperialists in assembling the Soviet Union and maintaining it by brute force. In lamenting the demise of that prison house of nations as the greatest geopolitical disaster of the 20th century, Mr.…