States and terrorist groups have long had a deadly relationship. During the 1970s and 1980s, almost every important terrorist group had some ties to at least one supportive government. Iran backed the Lebanese Hizballah, India aided the Liberation Tigers of Tamil Eelam (Tamil Tigers), and the Palestine Liberation Organization (PLO) (as well as its rivals) drew on support from a host of Arab states. At times, these connections were far-flung and seemingly bizarre. Libya, for example, helped arm the Provisional Irish Republican Army (PIRA), and Damascus had links to the Japanese Red Army (JRA). The Soviet Union and several Eastern European states backed Palestinian and Western European terrorist groups, among others. East Germany's last interior minister declared that his country had become “an Eldorado for terrorists.”

These links between governments and terrorists have lethal consequences. Chris Quillen finds that states are at least indirectly responsible for several thousand deaths at the hands of terrorists, a staggering figure that I believe may understate the scale of the violence. More generally, Quillen finds that “state-sponsored terrorists would appear both more able and more willing to kill in large numbers” than terrorists who lack ties to states.

With the end of the Cold War, one of the major sources of state sponsorship – the communist government in the Soviet Union and its puppet regimes in Eastern Europe – ended.