“Why Some Wars Get More Attention Than Others,” by Amanda Taub.
Conflicts gain sustained American attention only when they provide a compelling story line that appeals to both the public and political actors, and for reasons beyond the human toll. That often requires some combination of immediate relevance to American interests, resonance with American political debates or cultural issues, and, perhaps most of all, an emotionally engaging frame of clearly identifiable good guys and bad guys.
Most wars — including those in South Sudan, Sri Lanka and, yes, Yemen — do not, and so go ignored.