bamako mali president ibrahim boubacar keita head group five countries africa sahel region ask unite state remove travel ban chadian nationals say failure could affect chad security commitments security analysts express surprise chad key u.s. security partner since cold war name last week alongside north korea venezuela part eight-country travel ban chad army act bulwark local regional arm movements play critical role push back troop jihadist group boko haram make bid expand beyond northeastern nigeria 2015. troop continue hold front-line position unstable north mali jihadists oust government authorities five years ago recently february chad also key french ally host u.s. military train exercise special force part broad strategy empower regional troop g5 sahel security bloc consist chad mali niger mauritania burkina faso president g5 think decision could affect commitment chad show key partner fight terrorism g5 sahel beyond say keita statement send journalists late wednesday president ... call authorities favorably re-examine matter lift sanction chad add chadian officials express surprise decision early week call incomprehensible new u.s. measure end-date help fulfill campaign promise president donald trump make tighten u.s. immigration procedures align america first foreign policy vision white house say restrictions consequences countries meet new requirements vet immigrants issue visa mali president want u.s. reverse chad travel ban