Nature of external threat. Since fear is a powerful incentive for countries to increase their national power, countries that are threatened by others—or perceive that they are threatened—are likely to be motivated to increase their resources and their military capabilities necessary to enhance national survival. The extent of this motivating fear deriving from external threats can be judged by assessing the number and relative size of the direct challengers facing the country; the extent of any competitive arms racing that the country in question may be involved in, and the salience of the internal external nexus. By this latter is meant the extent of any external support for internal challenges facing the state.