Washington (CNN) A top National Security Council aide is leaving the White House after serving just a few months as national security adviser John Bolton's chief of staff.

Fred Fleitz, who joined the administration this summer, will soon return to the Center for Security Policy, the conservative think tank where he worked as vice president for policy prior to leaving for the NSC post.

"Fred Fleitz is a longtime friend and adviser. He's been a valuable member of the National Security Council team. I wish him the best with his next endeavor," Bolton said in a statement to CNN.

Fleitz will return as president and CEO of the Center for Security Policy starting in January 2019, according to the think tank. His first day back at the organization, however, will be November 1 -- one day after he officially leaves the White House, according to a senior administration official.

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