Consider a 17-year-old orphaned Syrian boy whose father was killed by the ruthless Bashar al Assad's regime for daring to seek reforms of his system of governance, and whose mother - still grieving over the death of her recently departed husband, being choked to death along with his younger brother and a younger sister, in a toxic gas attack from Syrian forces.
The youth's desire: justice for his family; his decision: to join Syria's opposition forces; his choice: the ISIL. Entrenched with hardened extremists, bombarded with fallible propaganda to justify Jihad, the Syrian teenager is voided of real world events and atrocities committed by his vehicular choice to justice in Syria.
Similarly, another youth of Arab descent in Birmingham, United Kingdom, disgusted by failed international efforts to bring peace to Syria, repulsed by the international impotence to hold Bashar al Assad responsible for gassing to death hundreds of Syrian children and flabbergasted that his society around him doesn't even break a stride in its day-to-day life as these events unfold in the Levant, this youth takes to the cause of Jihad to fight in Syria. Knowing that most Western nations overtly support some opposition forces in Syria, this youth finds solace in what he has deemed a worthy just cause as he joins the ranks of the ISIL.
What due notice could be delivered to these youths to surrender their ranks into the terrorist organization, and through what means? Whatever, some notification is warranted given some of the considerations that have lured many youths to the ISIL. Maybe many youths are looking for an exist from ISIL before the main push to destroy the group gains full execution stage?