The story of East Aleppo

There is so much to be written about regarding the fall of East Aleppo.  It is certain that Saudi regime and Qatari regime decided to abandon the Syrian rebels--and none of the supporters of Syrian rebels (in English or in Arabic) dare say that.  We don't know why and how those regime decided to abandon the rebels. There are indications of increasing divisions within GCC ranks, regarding Syria and other files.  There is also a story (told in As-Safir among others since) about Syrian regime infiltration of rebel ranks (and even leadership).  And there is also the story of deep divisions and infighting and street clashes between various rebel factions--even during the siege.  There is more to the story.