Hamas was officially established soon after, on 14 December 1987, forming other similar networks as "al-Mujahidun al-Filastiniun", such as the Abdullah Azzam Brigades. In mid-1991, in during the First Palestinian Intifada (1987-1994), the Izz ad-Din al-Qassam Brigades was established to provide Hamas with a paramilitary capability, thereafter becoming known as the armed branch of Hamas.