Whether the literature is new or old, two observations have repeatedly been made about intervention. The first is that intervention is a ubiquitous and endemic feature of the international arena. Guelke argues, for example, that intervention is ‘inherent in the nature of international society’ and, more recently, Bull sums up the views of a series of authors who all agree, he says, that intervention is a ‘built-in feature of our present international arrangements’. Not only do the great powers persistently intervene in the domestic affairs of small states such as Vietnam and Afghanistan, but there is also a tendency for small states to interfere inside each other's boundaries. Egypt, Syria, Cuba, Vietnam and a host of other small states have all conducted policies of intervention. It is also argued, moreover, that as the global economy becomes more interdependent, the potential for intervention is constantly on the increase. The decision to extend or refuse credit facilities, for example, can be seen as a very effective mechanism for intervening in the domestic affairs of the state.