The competition between Russia and the West has been heavily concentrated in Ukraine throughout history. But that is just one part of a much wider swath of territory in Eastern Europe that has been caught up in the great rivalry. Today, this territory consists of Belarus, Moldova and the Baltic states of Estonia, Latvia and Lithuania. Each of these countries has chosen its own path since the fall of the Soviet Union. Some have remained staunch supporters of Russia, others have enthusiastically embraced European institutions, and still others have shifted uncertainly between the two. In the next quarter century, the countries of Eastern Europe will begin to converge, forming a new regional bloc that will pool the economic and military strength of its members. ...