a metal detector at jfk left unguarded as passengers walked through. some setting it off. then apparently boarding flights. why didn't the tsa alert police for two hours? >>> the replacement pick. president trump's new national security adviser revealed. as the vice president tries to calm anxious allies overseas. >>> a new wave of bomb threats. evacuations at nearly a dozen jewish community centers across the country. tonight, parents alarmed. >>> scandal rocks uber. an urgent investigation as a former employee makes explosive allegations of sexual harassment against women. >>> dentist alternative. the new trend in getting your teeth taken care of. >>