A relevant feature of the USSR was the separation of the formal government, a federation, from the real political power, the unitary Communist Party, commanded from a single center, Moscow. The geographical borders of the union republics were a sham, so far as political control was concerned. They were designed to give non-Russians the illusion that they had political autonomy. In some cases borders were drawn in a calculated way to foster internal division, the better to exercise external control from Moscow. It is these borders, further modified by changes during and after World War II, that the USSRs successor states inherited. It is important to understand their origin if one is to comprehend the emotions involved in much of the conflict that has emerged in the post-Soviet space following the Soviet collapse.
For example, the frozen conflicts in the South Caucasus have roots in Stalins policy of creating pseudo-autonomous governments that were in fact controlled from Moscow by a unitary Communist Party. When Moscows heavy hand was lifted in the early 1990s, Armenia and Azerbaijan faced off in a struggle over Nagorno-Karabakh, an area with an Armenian majority that Stalin had made into an autonomous enclave in Azerbaijan. Once independent, Armenia seized control of it and established a corridor to it through Azerbaijani territory, but Azerbaijan still claims sovereignty over it. Likewise, tensions between Georgian leaders and the non-Georgian residents of Abkhazia and South Ossetia led to sporadic fighting, ethnic cleansing, the Russian invasion in 2008 and Russias recognition of the entities as independent, which neither Georgia nor most of the rest of the world accepts.
Some of the conditions that helped lead to Ukraines current fractured state were created during and after World War II, when Stalin attached large portions of eastern Poland and smaller portions of eastern Czechoslovakia and Romania to Ukraine. (He was not responsible, however, for transferring Crimea to Kievs jurisdiction. That happened after Stalin died, when Nikita Khrushchev was in control of the Communist Party.) As in the 1920s, borders were drawn or changed to suit Moscows convenience, without consultation with the residents or their consent. Nevertheless, when the Soviet Union collapsed, what had been local administrative boundaries became international frontiers overnight.