A transformation of political violence? Substitution and complementarity in terrorism and civil war

There is a widespread perception that terrorist attacks have become more frequent over the last two decades, and this appears to be backed up by common data on terrorism. This raises important questions about the relationship between terrorism as a tactic and other types of political violence. Some argue we see a transformation of political violence, where non-state actors targeting opponents indirectly through attacks on civilians are replacing conventional civil conflict where groups directly attack the state and security forces. We examine the relationship between terrorism and civil war in terms of potential substitution or complementarity between tactics. We present a series of analyses examining the relationships between terrorism and civil war, moving from trends in aggregate data over time to disaggregated analyses focusing on specific non-state actors and their relative allocation of direct and indirect targeting. Our analyses yield little evidence consistent with strict substitution, or that the apparent increase in terrorism reflects growth in indirect attacks in countries outside episodes of civil war. We find more evidence consistent with growing complementarity between terrorism and civil war, with increased use of terrorist attacks within civil wars over the period where terrorism appears to have increased. We examine the extent to which this increase in the use of terrorism in civil war coincides with observable changes in the characteristics of ongoing civil wars, and provide evidence of change points in actor profiles over time, including increasingly asymmetric conflicts where rebels may benefit more from carrying out terrorist attacks in an ongoing conflict.