The Islamic State first announced its presence in Libya in the eastern town of Derna in October 2014. The Islamic State's central leadership in Iraq and Syria bolstered this growth by dispatching advisors and redirecting flows of foreign volunteers to Libya. The Libyan affiliate began losing ground last year to local armed groups in Derna, Benghazi and Sabratha. The city of Sirte, however, remained untouched - until now.