Within weeks, forces loyal to Libya's Government of National Accord (GNA) recaptured large chunks of the coastal city of Sirte that IS jihadists had seized in June 2015 as a staging post for an expansion into North Africa. But they have failed to dislodge the last pockets of IS fighters, holed up in the fiercely-defended district of Al-Giza Al-Bahriya, in a costly battle that has left at least 667 dead and 3,000 wounded in GNA ranks.