As Syria’s war enters its fifth year, its refugees are fading deeper into the background. At a conference in Kuwait last week, countries promised more aid, but donor fatigue has left humanitarian organizations unable to help people like Deen, and that’s creating an opportunity for the Islamist militants who play a growing role in the conflict. This month, Islamic State and and al-Nusra Front militants took over much of the Yarmouk Palestinian refugee camp in Damascus.