Most governments shun terrorists both for their brutality and for the illegitimate nature of their tactics. Terrorism, after all, is murder. Moreover, terrorist groups often enjoy little support among the publics they purport to represent. Nor are terrorists promising horses to back, as they often have little chance of prevailing, particularly at the beginning of their struggles. Supporting a terrorist group also often carries a heavy price, as the group's opponents may seek to punish a sponsor. Not surprisingly, many states turn to diplomacy, economic pressure, or even conventional war before embracing terrorism. Yet despite being such unsavory and unpromising partners for states, many terrorist groups regularly receive state support. This support is forthcoming because the terrorist group can serve the strategic interests of foreign states, gain their leaders' sympathy for ideological reasons, or play a role in bolstering leaders' domestic positions.

Understanding motivations is vital both for predicting when a state might support a terrorist group and for determining how to end this backing. Regimes seeking to spread their ideology, for example, are in general far less amenable to standard forms of coercion or inducement, and such measures may even make them more likely to support terrorists. Regimes that are trying to gain a strategic advantage over their neighbors, in contrast, may be more willing to end their support if the costs become too high.