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. >>> dress for success. inspiring america by helping the suit make the man. "nightly news" begins right now. >> announcer: from nbc news world headquarters in new york, this is "nbc nightly news" with lester holt. >>> good evening to our viewers in the west. police were alerted to a serious security breach at a tsa screening checkpoint at new york's jfk airport this morning. the only problem, they were alerted two hours after ne
