NAIROBI — For Western nations, wars in far off places like Mali and Somalia cannot be ignored, though they might wish they could. US and European governments worry that Al Qaeda groups in Africa might threaten their citizens and interests — at home and abroad — and while France was willing to briefly intervene in Mali, most are wary of entrenching their own troops in potential quagmires on the continent. A cooperative model, where African armies supply the soldiers and the West provides the rest, might offer a way forward.