that to me is our priority. >> woodruff: senator catherine cortez masto from nevada, we thank you veryh. >> thank you. >> woodruff: turkish forces appeared ready to invade a kurdish area of syria today, and attack a force backed by the united states. this comes as syria's near- seven-year war grinds on, with the assad regime and its russian allies hammering opposition areas. so, as nick schifrin reports, an already-complex battlefield might soon become more so. >> reporter: on the turkish, syrian border, the turkish military appears ready for battle. they're amassing tanks, and firing artillery into syria. today turkish media said a hospital was targeted and destroyed. this is syria's northwest corner, controlled mostly by kurds. these are the same u.s.-backed kurds who helped liberate former isis headquarters raqqa. the u.s. wants to convert them to a 30,000-strong stabilization force. but turkish president recep tayyip erdogan told a raucous rally, the u.s.-backed group was a grave threat. >> ( translated ): a country that we call our ally insists on forming a terror army along our b