The events in Niger over the past few months have been alarming to watch. What began as a military coup now risks spiraling into a wider war in West Africa, with a group of juntas lining up to fight against a regional force threatening to invade and restore democratic rule in Niamey.

The junta have explicitly justified their coup as a response to the "continuous deterioration of the security situation" plaguing Niger and complained that it and other countries in the Sahel "have been dealing for over 10 years with the negative socioeconomic, security, political and humanitarian consequences of NATO's hazardous adventure in Libya." Even ordinary Nigeriens backing the junta have done the same.

The episode thus reminds us of an iron rule of foreign interference: Even military interventions considered successful at the time have unintended effects that cascade long after the missions formally end.