Over the past twenty years Russia has removed a set of territories from other countries. It removed the eastern part of Moldova, now known as Transdniestria; it removed the north-western Black Sea part of Georgia, Abkhazia; and it snipped away the territory controlling Georgia's main road to the Caucasus mountains, South Ossetia. The intention now appears to be to carry out the same operation in Crimea, removing it from Ukraine.
In each case, the procedure, not necessarily planned as such, has nonetheless followed a similar pattern. The territories contain large populations who, with varying degrees of justification, objected to the governments handed them in the post-Soviet order of newly independent states. The Slavs of Transdniestria feared Moldova would force them to speak Moldovan, and would unite with Romania. The Abkhazians wanted greater autonomy within, or independence from, Georgia. The South Ossetians, historically close to Russia, feared being cut off, within Georgia, from their northern kin in Russia, on the other side of the mountains.
In each case, clandestine Russian military support, helped by the presence of Russian bases in or near the territories concerned, found willing takers in the form of local military, paramilitary forces and self-proclaimed 'Cossacks'; Russian troops only became involved openly as 'peacekeepers'. In each case, the internationally recognised governments supposedly in charge of the discontented territories took military steps to enforce their claim. The presence of 'peacekeepers' and Russian-armed militias led to clashes, giving the Russian military cause to intervene decisively on the side of the separatists. (Newly independent Georgia's first military response to Abkhazian separatism was particularly heavy-handed.)
Russia's explanation is that the territories concerned should never have been allowed to go beyond Moscow's caring embrace, and that in each case, they are fulfilling the wishes of, and protecting, the majority of the territories' inhabitants. There is some truth in the latter point; but it is a dangerous argument for Moscow to make, given that it could be equally applied, against Russia, to Chechnya.
Russia has always stopped short of incorporating the three Russian-sponsored territories of Transdniestria, South Ossetia and Abkhazia – let's call them the RSTs – into Russia. But their status, whatever it is, has never been recognised by more than a handful of Russian allies, itself a small group. The RSTs exist as anomalies, outside international law; the only other comparable places in Europe are the Turkish-sponsored North Cyprus, which would rather move from its sponsor towards the EU, and Nagorno-Karabakh, where Armenia's actions at least have clarity. Russia effectively controls, backs and has responsibility for the RSTs, but has always denied invading and conquering them (or liberating them, as many local people would put it). At the same time, Russia is as sensitive to any perceived violation of its own post-1991 borders as China or the US.
As the RST scenario begins to play out on the Crimean peninsula, with its majority of disgruntled Slavs and a large minority of Tatars, deported en masse by Moscow within living memory, it is time to treat the RSTs as symptoms of a particular Russian problem; and to ask Russia to decide, in fact as well as in law, where it believes its borders stop, and the borders of other countries begin.