Yes, it does seem that in bypassing the Joint Chiefs of Staff, President Trump is putting our national defense at risk. There is no logical or obvious reason to bypass defense secretaries and experts in defense when discussing the safety of the United States. During his campaign, Trump promised to surround himself with experts who could advise him in areas he was unfamiliar. Who better to advise on national security than the Joint Chiefs of Staff?
No, Steve Bannon's constant presence, advising Trump, does not risk our national defense. While the president is a very powerful person, and his advisors wield mighty influence, it's my opinion that Steve Bannon does not present any more risk than did Valerie Jarrett under Obama, a person whom many on the right saw as problematic when she held the same position.
President Trump is not putting our national defense at risk. In the first place, Trump is not nearly as hawkish as his predecessors were. Secondly, Trump is trying to implement a smarter foreign policy. Finally, Trump is not really bypassing his Joint Chiefs of Staff, he just isn't publicizing everything he meets with them about.
The Joint Chiefs of Staff are still part of the inner circle. Just like many other things coming out of the press in the last week this current flap about Mr. Bannon being part of the NSC is much ado about nothing. The JCS will remain a vital role in the JCS and like Mr. Axlerod in Obama Administration, Mr. Bannon will now have a role in the NSC.