Security Dilemma and Ethnic Conflict

This article attempts to apply a basic realist concept, security dilemma, to account for civil conflicts following the collapse of the USSR. Publication year of the article (1993) shows that Posen was trying to come up with a theory by which future ethnic conflicts can be predicted, perhaps even be prevented. It seems that he assumed that the fall of imperial regimes will bring about an anarchical political environment in many countries where ethnic conflicts will be very likely. As the past decade has shown, number of ethnic conflicts did not skyrocketed and Posen's theory was not needed much. Nevertheless, this article is a nice example of the application of a realist concept to a state-level-situation. Posen first discusses security dilemma and then uses this concept to explain two cases: Why Croats and Serbs fought a war, and why Ukraine and Russia did not.
Realism argues that anarchical nature of the international system makes security the primary concern of the states. Just like in the international system, once imperial regimes collapse, they leave groups of people divided along ethnic/religious/cultural lines. Absence of a strong state creates an anarchy within the country and makes each group worry about its own survival. Among those groups, there will be competition for security. This competition will continue to a point at which the competing entity has got more power than needed for security. This situation will pose a threat to other entities and will be responded in turn.
Relative power is difficult to measure and is often subjectively appraised; what seems sufficient to one state's defence will seem offensive to its neighbors. Because neighbors wish to remain autonomous and secure, they will react by trying to strengthen their own positions. 
Posen identifies two conditions that make security dilemma more intense. First, when offensive and defensive military forces are more or less identical, states cannot signal their defensive intent by the kinds of military forces they choose to deploy. Any forces on hand are suitable for offensive campaign. Second, Offense is more effective than defense. Therefore, states will choose the offensive if they wish to survive.
"Strong national identity has been understood by both scholars and practitioners to be a key ingredient of the combat power of armies. A group identity helps the individual members cooperate to achieve their purposes. when humans can readily cooperate, the whole exceeds the sum of the parts." This observation is important for Posen because he regards "groupness" of the ethnic groups  that emerge from collapse empire as an inherent offensive military power.
Then Posen asks a critical question: How can a newly independent group assess offensive implications of the other group's identity power? The answer is history. For Posen, people look at the past and find out how that group behaved last time when it was not constrained. At this point history-making/history-writing should be noted because how old rivalries of groups are conveyed to the present generation influences one group's perception of the others.
As a realist, throughout the article Posen emphasizes that an insecure group will prefer offense to defense. He argues that there are two factors affecting offense-defense balance: technology and geography. He believes that technology is a rare determinant of the balance. Thus, we should not exaggerate the impact of technology, except nuclear weapons. Posen belives that although "groupness" is an important factor affecting security dilemma, if both sides have nuclear weapons, security dilemma will not be very intense. With regard to the impact of geography, Posen believes that how members of a group scattered in a country matters. When empires collapse, some groups will have greater offensive capability because they will be surrounding other groups. 
Comparison of two cases
- Croats and Serbs found each other's identity a threat because of the primitive military capabilities. In the Russia-Ukraine case, nuclear weapons mute the conventional competition, making group cohesion less of a military asset.
- Both Croats and Serbs were likely to find allies at international arena. But in the other case Ukraine knew that compared to Russia it would be more difficult to find allies. Posen argues that Croatia overestimated the reliability and influence of the Federal Germany as an ally.
- History of Russia and Ukraine is more conducive to peace than that of Croats and Serbs. Competition of the empires during the middle ages made Croat-Serb relations tense. But during the communist war and famine of 1930-35, Ukrainian president blamed the bolshevicks, not the Russians.
- Serbs had many incentives for preventive war while Russia had few incentives. Serbs outnumbered the Croats only two to one and enjoyed no economic advantage. But Russia's human and material resources were three times more than Ukraine's, and it was unlikely that the balance of military power will soon shift against Russia.