via Daily Kos: Trump Has Illegally Bypassed Senate Consent on Bannon Appointment to NSC

[fishwax]

47. I don't think it requires senate confirmation ... Bannon is invited to all the meetings

The President can invite, I would imagine, anyone he likes. There are routinely people who are invited to the NSC meetings who aren't confirmed by the senate, like the white house counsel and the chief of staff.

The thing that's got people (rightfully) up in arms is the shakeup on the Principals Committee, which is a subset of the National Security Council. It isn't the same thing as being on the National Security Council. So Bannon isn't really a member of the Council (the membership of which is established by the law posted elsewhere in this thread); he's just invited to all the meetings of the cabinet-level members.

All of this is not to say that this isn't a dangerous step, or that the elimination of the Chairman of the Joint Chiefs or the Director of National Intelligence from the Principals Committee ought not concern us.