Croatian case provides one possibly relevant comparison with the Ukrainian crisis. Apart from that outcome, there are three other endgames, which reflect the fact that different players are involved and that better procedure and outcome is available, but is rather unlikely to be adopted. The implication is that the conflict will be a protracted one with no endgame in sight.
The Example: Croatia
In summary, once Croatia declared independence (in mid-1991), Serbian minority seceded with the help of the Yugoslav (basically Serbian and Montenegrin) army and a score of paramilitaries. In about half a year, international intermediation forged an agreement which stopped the intervention, some occupied (informally annexed) territories were eventually returned, overt military support was discontinued, and UN presence was established in the territories controlled by the Serbian separatists. Indirect and direct negotiations were held over the years with no success. In the end, Croatian forces reclaimed the territories in the campaigns in the spring and summer of 1995. There was mass exodus by the Serbs.
The outcome was predictable, though not the details of how it would come about. Once, the direct and sizeable support for the separatist was discontinued and the UN presence was established, there were only two possible outcomes: negotiated settlement or a takeover of one kind or another. Why the former did not work and why the later was to be expected?
Before that, why only these two alternative outcomes? The reason is that once UN gets involved, Security Council would have to agree on an outcome that runs counter the territorial integrity of a state. Barring such an agreement, UN can only keep the peace and cannot support any territorial changes (except if agreed by the parties involved). So, once the UN is on the border and is keeping the peace in the contested territories, reintegration is the only possible outcome, except if the parties in conflict agree otherwise.
Now, why did the Serb leaders in Croatia reject any agreement short of secession? The reason is that they would have to severe their ties with the outside supporter, Serbia in this case, to stop acting as its exponents, and would have to face a legitimacy test, which eventually would lead to their replacement. So, it is in the interest of these leaders to maintain the cease-fire, but not to make peace. This can change if external support is completely discontinuedin the face of government’s military assault (which eventually came about in 1995).
Of course, if the external support disappears, the other outcome, the other type of reintegration, becomes more probable. But, that outcome becomes ever more probable with the passage of time in the circumstances established by the UN peace-keeping presence because the state will keep getting stronger, while the separatists will keep getting weaker. In Croatia, the state-building process took few years and so did the process of the build-up of its military. Separatists, on the other hand, became ever more dependent on Serbia for just about everything with military support being increasingly inadequate to resist the coming Croatian assault.
In these circumstances, the UN cannot stand in the way of the activities of the state, even military ones, to reclaim the control over its territory. Again, a decision by the Security Council would be needed to take a collective action to stop government’s forces. Individual countries or coalitions can support the government, but not the insurgents, at least not under the UN mandate. Of course, permanent members of the Security Council can choose to act differently because they have veto power. This is an important caveat that did not apply to Croatia, as no veto power was used.
Thus, one can see on the Croatian example that once cease-fire is agreed on, external support is discontinued or limited, and the UN’s presence is established, either there is a consensual reintegration or a coercive one. Put differently, there are three conditions for the Croatian-type of an outcome: external support is discontinued, UN (and OSCE, EU, and other multilaterals) presence is established, and central government strengthens (politically and militarily).
Other cases with different outcomescan be understood by looking at whether these conditions are satisfied. In the case of Cyprus, external presence is permanent. Basically, Turkey keeps military presence in Northern Cyprus. UN is present there, but the Security Council would have to agree to collective action to forcefully reintegrate the country, which does not seem to be a decision anybody wants to make.
In the case of Abkhazia and South Ossetia (and Transdniestria), in addition to permanent presence of external military forces, there has been some (explicit or implicit) UN support for the Russian military, i.e. peacekeeping presence. So, military takeover by the government is infeasible and also will not get the support by the UN given Russia’s power to veto. These types of situations are mostly possible in the case of a permanent member of the Security Council being directly involved or indirectly by supporting a client state.
Finally, the centre may not hold, in which case the UN can come up with a solution, which either means secession or an imposed constitution. These would be the cases of Kosovo and Bosnia and Herzegovina respectively. This could be an outcome of either internal disintegration, or of external interference, which leads to state failure, or both. Of course, the requirement is that the Security Council can agree and the parties themselves cannot. Otherwise, internal settlement trumps imposed solutions while lack of agreement in the UN may lead to protracted civil war or other types of entrenched conflicts.
On to Ukraine
There are more than few similarities between Croatia and Ukraine. There is external intervention, an annexation of part of territory by Yugoslavia (Serbia and Montenegro) and Russia respectively, external military and every other (e.g. propaganda) support for the secessionists, but also the resilience of the government, the process of democratic and military strengthening, and growing international concern. The difference is that UN and other multilateral involvement is difficult to forge because the mandate would have to be to secure the border, keep the peace, and facilitate negotiations with the aim at a political solution. That, however, would lead to one or the other of the possible outcomes as in the case of Croatia: peaceful or coercive reintegration. Even the former outcome will be increasingly unfavourable to the secessionists with the passage of time, and, of course, it will end the political carrier of their leaders. But, such an outcome would also be unacceptable to Russia, which has to agree to any UN action in Ukraine. It is hard to see that it would do that before it can be sure that it will get the outcome it prefers. And that cannot be the one that makes its political and military involvement unjustified ex post.
So, it is unlikely that Russia will agree to discontinue the support for the separatists and to invite the UN presence with a mandate similar to the one in the Croatian case.
One can assume that the preferred outcome for Russia would be the one that is similar to the frozen conflicts in which it has been able to keep military presence with or without the consent by the Security Council. That will lead to a protracted internal and external conflict in and for Ukraine and long term strained relations in Europe and globally. That will test Ukrainian political, economic, and military capacities and the commitment of the EU and the USA to its stability and integrity. Direct military involvement is inconceivable, but political and economic support will certainly have to be quite significant and enduring. The collapse of Ukraine as a state, its balkanisation so to speak, does not seem likely from within and is certainly not the preferred outcome for most anybody in the EU.
In the case of Croatia, the country being initially rather weak in military terms, Serbia had about four years to mull over its incentives to keep to the territories or to let them go. In the Ukrainian case, the time is in all probability much shorter and indeed, it may already have expired. So, Russian decision cannot be postponed for too much longer. What are the incentives that may determine it?
One is internal politics that may on balance favour deeper and more explicit involvement. This issue is complex, but clearly decisive. The main consideration, in all probability,is the risk to government’s legitimacy if it is seen as losing in a conflict that is otherwise almost impossible to justify. Victory is the only justification, which is why the government and the leadership is in a bind in Ukraine.
The other issue is about economic incentives. The costs to open intervention in Ukraine in terms of the access to EU markets and world financial services are hard to estimate. There is an equilibrium condition somewhere out there, but it is not easy to define. Taking the gas and oil markets as an example, clearly higher involvement that will be a long-term one will have adverse effects for Russian oil and gas business. So, the conflict and Russian involvement need to be set at the level that does not risk its position of major supplier of oil, gas, and raw material to Europe and at prices which do not induce investment in alternative sources of energy and in alternative technologies. Russia has invested a lot in the monopolisation of these markets in Europe to give up on them hastily.
On balance, the incentives seem to work for persistent Russian support for the separatists and a protracted conflict that may be as open as domestic and economic incentives warrant.
Better strategy and endgame, that would avoid Croatian ethnic cleansing and the protracted conflict, which one could recommend, is that of strengthened legitimacy of all the actors (through democratic procedures) in Ukraine and of constitution building. This is, in principle, the only process that leaves all the possible outcomes open. It also allows the parties to reach a consensus. One example is Macedonia, which again highlights the role of the external intervention and of the international response, which led to internal constitutional adjustment, which was supported by democratic legitimisation of the parties to the constitutional agreement. The stability of the agreement is an added issue, but the way to deal with it is the same.
But, the experience of post-totalitarian constitution-building is quite rich in Europe and provides for a variety of models that can be usefully tested in the Ukrainian case. All totalitarian states were like cease-fires in civil wars, so the situation is comparable to open internal conflicts, except for the external intervention. The important lesson is that once a legitimate process of putting together a constitution is initiated, the history of wars, civil wars, or deep differences, e.g. religious or ideological ones, seize to be insurmountable obstacles to a consensual agreement, whatever it might be.
Even if there is a persistent interest for a region to secede, this process allows for that outcome. The example of the secession of Montenegro is the relevant one here. It seems to be the case, however, that there is no clear democratic and legitimate support for secession in the East of Ukraine, which is why it is not in the interest of the secessionist leaders to give up arms and engage in politics of constitution building.
The Croatian outcome is not the one that Russia seems content with, which makes it probable that it will continue to intervene in Ukraine with more or less open military support for the secessionists. The aim being to either (i) informally occupy parts of Ukraine creating a frozen conflict type of a setup, or (ii) work for the failure of the Ukrainian state. Otherwise, there is a democratic way to work out a constitutional set up in Ukraine, which could be supported by international cooperation and avoid these other clearly inferior outcomes, but though “the solution ‘exists’; the problem is how to ‘find’ it”, to quote Paul Samuelson.