Friday saw more of the expected house-cleaning and reshuffling at the Pentagon under Pete Hegseth, as Navy chief of staff Jon Harrison has been fired.

"Jon Harrison will no longer serve as Chief of Staff to the Secretary of the Navy. We are grateful for his service to the Department," a Department of Defense (DOD) official said.

Harrison had been appointed to the United States Arctic Research Commission by Trump in 2020, and interestingly he from the start of the current administration became a key architect implementing Hegseth's and Trump's new vision for the Pentagon.

"The sudden ouster, according to two defense officials and a former defense official, follows the confirmation this week of Navy Undersecretary Hung Cao," Politico writes.

The publication further notes that Harrison made changes which also sought to limit the power and influence of the undersecretary job:

POLITICO previously reported that Phelan and Harrison had reassigned several aides who were supposed to help Cao navigate the role once he’s confirmed. They had also planned to interview all future military assistants for Cao to ensure decisions came from the secretary’s office.

Cao is a high-profile Navy veteran and former Republican Senate candidate in Virginia who President Donald Trump nominated for the post.

The ouster follows months of musical chairs inside the Pentagon. Hegseth fired several top aides earlier this year and removed the chair of the Joint Chiefs, as well as the uniformed leaders of the Navy, Air Force and Coast Guard.

As another example, in August Lt. Gen. Jeffrey Kruse had been ousted from his role as director of the Defense Intelligence Agency (DIA).

The official reason disclosed is "loss of confidence". While the DIA is lesser known among the nation's major intel agencies like the CIA or NSA, it coordinates all military intelligence among US armed forces, and is mostly staffed by civilians - but under DoD leadership.

Hegseth also removed Vice Adm. Nancy Lacore, head of the Navy Reserve, and Rear Adm. Milton Sands, a Navy SEAL in charge of Naval Special Warfare Command, from their posts, according to officials.