Flight Path Data News Today

>> reporter: the pentagon providing evidence it says shows assad was behind the war crime. the flight path data of the syrian warplane. and tonight, the u.s. military looking into whether the russians knew about that chemical attack or assisted in any way. today at the united nations, ambassador nikki haley warned that the u.s. could strike again. >> the united states took a very measured step last night. we are prepared to do more. >> so lets bring in martha, live in washington. were learning t...