Egypt and Syria have been “disappearing” their citizens. This is why countries do it.

Human rights organizations recently reported that activists in Egypt have disappeared after they were stopped at government checkpoints. In Syria, the regime has disappeared thousands in the midst of its brutal civil war. Repressive states in the Middle East have increasingly added the “disappearing” of regime opponents to their means of violence.

Enforced disappearance is the state’s refusal to acknowledge that it is holding a person it has detained or to disclose the fate of that person. The United Nations has documented more than 55,000 disappearances in 107 countries since 1980, with the practice spreading across countries over time.

Disappearing opponents may seem like an effective means to squash a threat to the regime — especially for regimes under the watchful gaze of human rights organizations that might disappear citizens to hide their repression. But it is not that simple. Regimes known to have inflicted disappearances, such as in Guatemalaand El Salvador, flagrantly used overt forms of violence at the same time.

Countries also differ in how they use this tactic. Despite facing similar opposition to their 1970s military regimes, Argentina disappeared at least 10,000 citizens, while Uruguay disappeared only a few dozen. Why are some regimes willing and others unwilling to disappear opponents in carrying out violent repression?

My research shows that states use disappearances — as opposed to other forms of repression — when they cannot “read” the nature of their opposition. States use disappearances when they see their opponents as having wide but shallow support, making it difficult to identify who supports or might join the opposition. The regime are attempting not only to coerce a few activists but to broadly demobilize the opposition.

This is not just punishment for lawbreakers. It is intimidation of broad sectors of society to demobilize them. To achieve efficient and enduring intimidation, states apply the rationale of hostage-taking to coerce opponents. They disappear citizens to gain the family’s and acquaintances’ compliance with their demands. Just as in kidnapping, the state holds coercive leverage by physically holding the victim, cutting off other avenues to free the victim except compliance — and having leverage as long as the victim is believed to be alive.