Finally! The SDF have reportedly commenced their entry from the east. The road ahead will not be easy for the SDF.
I should clarify Brett McGurk's comment below. ISIS can if they wish cross the Euphrates and head to Dier Ezzor however that 2 larger ISIS convoys trying to do so have been destroyed by the Russian Air Force. Basically ISIS fighters can leave or desert their posts but without any heavy weapons or vehicles (other than motor bikes and the like) or they can surrender to the SDF.
The offensive will see coalition air strikes onspecifically identified ISIS fighting positions but it won't be like Mosul, Aleppo or Al Bab where most of the city is destroyed.
Applying PKK styled tactics the YPG and some aligned FSA fighters Raqqa will deploy more like Viet Cong units with the view to beating ISIS at their own game. There will likely be sleeper cells, sniper units, embedded sympathizers and assassinations of ISIS commanders. The aim will likely be to weaken ISIS' fighting positions from within. Locals forced at gun point to join ISIS may be provided opportunity to leave. And while this is happening a more conventional attack involving other coalition groups including the bulk of SDF Arab fighters will slowly ebb away at the outer defenses. US Marines are providing artillery support from a distance.
ISIS hardliners will have deployed thousands of booby traps, and they will use human shields.
The likely time frame maybe 4 to 6 weeks depending on whether ISIS's unwilling conscripts put up any resistance. My guess is that half of the ISIS force of around 4500 fighters don't want to fight however the other half (hardliners including foreign jihadists) have nowhere to go to and no options left.
The current spate of global terror attacks is an attempt by ISIS to distract attention from their impending defeat in Raqqa.
