Inside Trump's Controversial National Security Council Changes

— -- When Donald Trump signed a memo last Friday outlining the structure of his National Security Council -- something that is generally pro forma -- eyebrows were immediately raised at some of the moves.

The biggest change: Trump decided to make his chief strategist and former Breitbart executive, Steve Bannon, a "regular attendee" of the principals committee -- meaning he'd have a prominent seat at all NSC meetings, including the lower-level ones that the president doesn't normally attend.

Given Bannon's limited experience in the national security realm (he served as a surface warfare officer in the Navy for seven years) and the political nature of his involvement in both media and Trump's campaign, that decision is considered by some observers to be unusual.

A number of former Obama officials said there was no equivalency in the previous White House to Bannon's new role as a principal committee member. For instance, David Axelrod, Obama chief adviser and political campaign strategist, occasionally sat in on NSC meetings, but only as an observer, these officials said.

In an interview over the weekend, former acting Director of the CIA, Mike Morell, called Bannon's appointment "unprecedented." Sen. John McCain, R-Arizona, called Bannon's appointment a "departure from any National Security Council in history" and said the reorganization is "of concern."

Bannon is best known for his time at Breitbart and the incendiary headlines that website produced, but he does have other credentials. A profile on Breitbart says he attended college at Virginia Tech, he got a master’s degree in national security studies from Georgetown University, and then went on to get an M.B.A. from Harvard Business School.

Bannon's publicly available military service record shows he was a Navy Reserve officer from October 1976 to October 1983 and served on a Navy destroyer for 10 months in 1983. He worked a job at the Pentagon as an assistant to the Chief Naval Officer during the same years he was at Georgetown by night and left the Navy with the rank of lieutenant, the records show.

The memo Trump signed also limits the attendance of the Director of National Intelligence and the Chairman of the Joint Chiefs of Staff in the principals committee, a move that former Obama National Security Adviser Susan Rice called in a tweet "stone cold crazy." She was also critical that the memo made no mention of the role for the Director of the CIA.

President George W. Bush's 2001 organizational memorandum for the NSC issued in 2001 created a similar structure for the top intelligence officer and the Chairman of the Joint Chiefs of Staff. Likewise, President Obama also made no mention of the CIA Director in his memo.

White House spokesman Sean Spicer fired back Monday, saying that the DNI and the Chairman of the Joint Chiefs are welcome to any meeting they want to attend as members of the NSC. He also announced that Trump had amended the memo “to add CIA back into the NSC.”

"What we've done is made sure that on issues of homeland security and domestic policy, they are always welcome attend, 100 percent," Spicer said. However, they are not required to attend meetings outside of their expertise, "like pandemic flu or other domestic type" issues, Spicer said.

However, the memo was not that clear. The exact language said the two "shall attend where issues pertaining to their responsibilities and expertise are to be discussed" and it was unclear they could attend any meeting they liked.

One former Obama official who spoke to ABC News also criticized the fact that Trump allows for his vice president to oversee full NSC meetings when he is not able to attend, an option Obama didn't allow. Again, that structure was identical to President George W. Bush.

Even Robert Gates, the secretary of defense under Bush and Obama, interpreted the reorganization as a slight to those critical advisers.

"My biggest concern is there are actually, under the law, two statutory advisers to the National Security Council, and that's the director of [national] intelligence, or the DNI, and the chairman of the joint chiefs of staff," Gates told ABC News' Martha Raddatz on "This Week." "They both bring a perspective and judgment and experience … that every president — whether they like it or not — finds useful."