A White House source estimates more than 60 percent of employees at the National Security Council are not Trump administration appointees, but career officials who were appointed to the White House from other agencies under the Obama administration.
The source said there are "whole departments" at the NSC with only one Trump appointee.
"I think the lesson here is that these things are going to continue to happen until the Trump White House does a serious housecleaning," said Fred Fleitz, a former CIA and Bush administration official.
"Now under civil service rules, it's difficult to fire them and I'm not sure they should be fired, but they can be reassigned. And people who are going to promote the president's policies rather than undermine them — he needs to put those people in place," he added.