raqqa syria gutted four-storey build five u.s.-backed fighters turn frontline fortress babel peer islamic state position 150 meter away jihadist militants expect make last stand stronghold self-proclaimed caliphate corner desperate raqqa city euphrates river serve de-facto syrian capital since 2014. let daesh come ready explosives drop downstairs say babel nom de guerre fellow members u.s.-backed syrian defense force occupy frontline build three weeks prepare final showdown islamic state group also know isis isil daesh sdf fighters position well prepare case corner militants attempt attack front porch step demolish leave drop basement cross climb section iron fence makeshift ladder defenders pull inside plastic bottle strew across floor squeak step alert intruders months intense fight heavy u.s. bombardment sdf surround islamic state militants small part city kurdish arab militias sdf close u.s.-led air raid increase expect fierce fight mark final stag campaign daesh regularly launch small raid even behind position yesterday attack build opposite try push toward us kill retreat hospital babel say sdf units clear view raqqa hospital one islamic state last strongholds city line build occupy northwest apartment block hospital flatten air strike commanders say hospital nearby stadium jihadists say hold civilian hostages make last stand babel unit hold front line ahead anticipate final push fire militants whenever spot last nights shin spotlight hospital towards line really see say another fighter unit say sniper fire islamic state recently reduce possibly mean conserve ammunition intense fight come sdf field commander say sunday assault begin soon part final push islamic state focus initially surround stadium hospital already encircle daesh amass prepare fight last stage resist surrender die commander give name ardal raqqa say u.s. coalition spokesman ryan dillon cautious call current stage offensive final assault whether final assault assault characterize either way dillon say phone fight concentrate around complex national hospital stadium say sdf predict ahead major push june could take weeks drive islamic state raqqa prove overly optimistic militants hold months far use civilians cover tunnel launch counter attack snipers countless booby trap slow sdf advance many wound especially snipers daesh snipers often shoot wind kill target whoever come save injure comrade babel say one shake sdf fighter nearby base last week show cut face sniper bullet ricochet u.s. spokesman dillon sdf fighter babel say islamic state fighters surrender day saudi fighter escape hand guy surrender usually families babel say interrogations surrender militants reveal dig tunnel hospital stadium say dillon say several militants leaders surrender recent weeks grow trend say front line sdf fighters say morale high one fighter belt pop music units walkie talkie hopefully do soon babel say fighters raqqa front line brace final showdown islamic state