"Throughout its history, Russia has been a special case. It arrived late on the European scene—well after France and Great Britain had been consolidated— and none of the traditional principles of European diplomacy seemed to apply to it. Bordering on three different cultural spheres—Europe, Asia, and the Muslim world—Russia contained populations of each, and hence was never a national state in the European sense. Constantly changing shape as its rulers annexed contiguous territories, Russia was an empire out of scale in comparison with any of the European countries. Moreover, with every new conquest, the character of the state changed as it incorporated another brand-new, restive, non-Russian ethnic group. This was one of the reasons Russia felt obliged to maintain huge armies whose size was unrelated to any plausible threat to its external security. Torn between obsessive insecurity and proselytizing zeal, between the requirements of Europe and the temptations of Asia, the Russian Empire always had a role in the European equilibrium but was never emotionally a part of it. The requirements of conquest and of security became merged in the minds of Russian leaders. Since the Congress of Vienna, the Russian Empire has placed its military forces on foreign soil more often than any other major power. Analysts frequently explain Russian expansionism as stemming from a sense of insecurity. But Russian writers have far more often justified Russia’s outward thrust as a messianic vocation. Russia on the march rarely showed a sense of limits; thwarted, it tended to withdraw into sullen resentment. For most of its history, Russia has been a cause looking for opportunity."