Libya broke up in 2011. Terrorists, already in Libya, mingle with Tuareg rebels and invade Mali in 2012. in Nigeria, Boko Haram lays the groundwork for terrorism in 2009. On both sides, the control of security escapes the states. Little by little, the security situation is getting worse in Mali, Mauritania, Niger, Nigeria and Chad. Blue helmets are already present in Mali. The French force Barkhane and the national forces of the five countries are slow to pacify the region. The presidents of the states created the Multinational Joint Task Force in Lake Chad and the G5sahel Forces with its three counterterrorism spindles. The results are mixed. The populations are angry with the authorities in charge of the fight against terrorism. They ignore the real causes of terrorism in the Sahel. A combination of social, economic, and political behaviors has led to the presence of terrorists in a territory that is, in principle, excluded from terrorist activities. Some say that terrorism is the work of the great powers, while others point to the poor governance of states. Who and who serve terrorism? The book lifts the veil on the question.