Egyptian prosecutors have referred 28 terror suspects in two separate cases to court on charges of joining local affiliates of the ISIS group and al-Qaeda. They said Monday the suspects were plotting attacks against security forces and the headquarters of the high state prosecution in Cairo. They say only 17 of the 28 suspects are in custody. No date has been set for their trials. An ISIS affiliate based in northern Sinai has carried out attacks across Egypt in recent years, mainly targeting security forces and the countrys Christian minority. Egypt has been battling radical militants for years, but the insurgency gathered strength after the 2013 military overthrow of an elected but divisive Islamist president.