War and other forms of international violence are used as leverage to try to improve
the terms of settlement of conflicts.
Many theories have been offered as general explanations about when such forms of
leverage come into playthe causes of war. Contradictory theories have been proposed
at each level of analysis and, with two exceptions, none has strong empirical
support. Thus, political scientists cannot reliably predict the outbreak of war. The two
exceptions are: (1) that there are virtually no societies in which war and intergroup violence
as means of leverage are unknown, and (2) that democratic states almost never
fight wars against other democracies.
States come into conflict with each other and with nonstate actors for a variety of reasons.
Conflicts will always exist among international actors.
Territorial disputes are among the most serious international conflicts because states
place great value on territorial integrity. With a few exceptions, however, almost all
the worlds borders are now firmly fixed and internationally recognized.
Conflicts over the control of entire states (through control of governments) are also
serious and are relatively likely to lead to the use of force.
Economic conflicts lead to violence much less often, because positive gains from economic
activities are more important inducements than negative threats of violence.
Some particular kinds of economic conflict, however, have special implications for national
Drug trafficking creates several kinds of conflict that draw in state and nonstate actors
Ethnic conflicts, especially when linked with territorial disputes, are very difficult to
resolve because of psychological biases. It is hard to explain why peoples loyalties are
sometimes to their ethnic group, sometimes to a multiethnic nation.
Fundamentalist religious movements pose a broad challenge to the rules of the international
system in general and state sovereignty in particular.
Ideologies do not matter very much in international relations, with the possible exception
of democracy as an ideology. State leaders can use ideologies to justify whatever
actions are in their interests.
When violent means are used as leverage in international conflicts, a variety of types
of war result. These vary greatly in size and character, from guerrilla wars and raids to
hegemonic war for leadership of the international system. Along this spectrum of
uses of violence, the exact definition of war is uncertain.
Like other violent means of leverage, terrorism is used to gain advantage in international
bargaining situations. Terrorism is effective if it damages morale in a population
and gains media exposure for the cause.
The September 2001 attacks differed from earlier terrorism both in their scale of destruction
and in the long reach of the global al Qaeda terrorist network. The attacks
forced dramatic changes in U.S. and worldwide security arrangements, and sparked
U.S. military intervention in Afghanistan to overthrow the Taliban regime and destroy
the al Qaeda bases there.