No real surprise. Several news media have recently started reporting about rumours that Trump suspects Steve Bannon to be involved in the white house leaks, and that Bannon's job is in jeopardy. Trump's latest move suggests that those rumours were indeed correct.
https://www.vanityfair.com/news/2017/08/steve-bannon-h-r-mcmaster-white-house-leaks
https://www.axios.com/steve-bannons-job-in-jeopardy-trump-suspects-him-of-leaking-2472208484.html
http://www.zerohedge.com/news/2017-08-13/bannon-jeopardy-trump-suspects-key-advisor-source-leaks
http://www.dailymail.co.uk/news/article-4785896/Trump-reportedly-believes-Bannon-leaks.html
http://thehill.com/homenews/administration/346356-trump-suspects-bannon-of-leaks-report







