Pentagon chief of staff Kevin Sweeney was reportedly forced out by the White House.

Sweeney, a retired Navy rear admiral, announced Saturday that he was resigning, saying in a statement, "I've decided the time is right to return to the private sector."

But a source told CNN's Jake Tapper that Sweeney's exit was orchestrated by the White House.

Sweeney departs less than a week after Jim Mattis left his post as defense secretary. Sweeney had worked with Mattis when he led the U.S. Central Command and as chief of staff advised and counseled Mattis.

Mattis announced his resignation in December after President Trump announced his intent to withdraw troops from Syria.