Internationalized internal armed conflicts have become a common feature of the past decades. In numerous civil wars foreign armed forces have intervened in favour of one or the other party and thereby attempted to influence the outcome of the conflict. Various causes have led to this development. One of them is the increased interdependence of States, as a consequence of which every civil war will affect other States and, conversely, the attitudes of other States may have an impact on the outcome of the civil war, even without any intervention. Another cause can be found in the world's ideological cleavage which divides nations and results in the overlapping of internal and international conflicts. Among further causes we can mention the existence of military blocs and of regional groupings which have an interest in preventing the overthrow of régimes within the bloc and tend to encourage alterations in other blocs. Another factor to be taken into consideration is the prohibition of the use of force in international relations. Whereas in earlier times States waged open wars in order to increase their power, today, due to the prohibition of the use of force, they rather endeavour to achieve the same result by interfering in the internal affairs of other States. Interference in internal conflicts is often a substitute for an international war. The instability of many contemporary régimes, mainly of the Third World, further favours the internationalization of internal conflicts.