Relatives of Jordanian pilot Lt. Muath al-Kaseasbeh, who was captured by ISIS militants in Syria, protest in front of royal palace in Amman, Jordan, Tuesday. Jordan has suggested it might be willing to hold a prisoner exchange for his release. JAMAL NASRALLAH/EPA /LANDOV hide caption

itoggle caption JAMAL NASRALLAH/EPA /LANDOV

Free Syrian Army fighters run behind sandbags in Daraa Al-Mahata, in southern Syria, on Jan. 21. Many moderate rebels joined the uprising to fight against President Bashar Assad, but the U.S. plans to train them to fight the self-proclaimed Islamic State. Wsam Almokdad/Reuters/Landov hide caption

itoggle caption Wsam Almokdad/Reuters/Landov