that they're there to fight isil. >> a u.s. official tells cnn, so far rebel groups have been able to thwart at least limited parts oof the russian and syrian advances. even in the face of this brutal rocket system essentially a giant flame thrower. but a top congressional democrat says the u.s. has to do more. >> that might mean a no-fly zone in the southern part of syria and sending a message that they send up helicopters to barrel bomb people, we're going to take those down. >> u.s. and nay co officials making it very clear, their assessment, the russians are still overwhelmingly striking anti-regime, anti-assad forces and maybe have only conducted a small number of attacks, if any, against isis. barbara starr, cnn, the pentagon. james gal vin is with us right here in the studio.