Is nbc nightly news with brian williams. Good evening. The question was raised at the pentagon today at the very top, the secretary of defense, if this terrorist group isis is capable of what we have seen so far, the rampant violence and gruesome killings, most recently the awful execution of an american journalist carried out on camera, then what risk does isis perhaps pose to the United States . The answer from the boss at the pentagon today indicates its a question the u. S. Is concerned about. And in a violent world for good reason. Its where we begin tonight with White House Correspondent Kristen Welker traveling with the vacationing president tonight in marthas vineyard. Kristen, good evening. Reporter brian, good evening. Today the secretary of defense spoke to reporters for the First Time Since james foley was executed. And he didnt mince his words about the immediate threat that isis poses. The secretary of defense acknowledged today what armies in syria and iraq already knew,