There are, however, relatively new centralizing forces that are changing the system. Another structural characteristic is determined by who the major actors in the system are. Currently these are sovereign states, but intergovernmental actors and transnational actors are becoming more numerous and important. A third structural characteristic is a system's scope and level of interaction. The current system is becoming increasingly interdependent, with a rising number of interactions across an expanding range of issues.
Economic interdependence is especially significant.
Among power relationships, an important factor is the number of poles in a system. Bipolar systems, for instance, may operate differently and be more or less stable than multipolar systems. The pattern of concentration of power is another system characteristic. Whether poles are relatively equal or unequal in power, the shifts in relative strength influence behavior in the system. Power changes in the system when there are shifts in the sources of power or when conditions within major actors affect their tangible or intangible power assets.