With little fanfare, Algeria, Mali, Mauritania, and Niger have initiated a program of close cooperation against Islamist terrorists in the Sahel (the semi-desert region at the southern edge of the Sahara). This includes agreements on the sharing of information and common communications protocols, to facilitate rapid response to problems. But it goes well-beyond those, to establish some rights to hot pursuit and guidelines for collaborative operations against terrorists, such as that which Mauritania and Mali are currently conducting in the northern part of the latter country.