Defense Secretary Lloyd Austin called for an "immediate suspension" of the department's advisory committee operations as it conducts a top-down review and ordered the removal of all advisory board members by mid-February, an internal memo said.

Austin, who was nominated by President Joe Biden and confirmed by the US Senate in late January, said that the Defense Department's review was being conducted to "align with our most pressing strategic priorities and the National Defense Strategy."

"Advisory committees have and will continue to provide an important role in shaping public policy within [the Department of Defense]," Austin said in his memo to the department. "That said, our stewardship responsibilities require that we continually assess to ensure each advisory committee provides appropriate value today and in the future, as times and requirements change."

In the memo, Austin says that "conclusion of service" for all advisory board members will take place no later than Feb. 16.

News of the changes to the department's advisory committees was first reported by The Wall Street Journal on Tuesday afternoon. The latest news follows a report last week from Politico that the Pentagon had halted all appointments to the boards.

The various Pentagon advisory boards are comprised of civilians appointed by a defense secretary to provide bipartisan counsel on matters that range from business to military policy.

The intended nonpartisan goals of the committees were heavily scrutinized after acting Defense Secretary Chris Miller — who was appointed by then-President Donald Trump after he fired his defense secretary following the November election — purged the boards and installed a number of loyalists in the final weeks of the administration.

After Miller abruptly emptied out most of the Defense Policy Board, he cleared out much of the Defense Business Board. Changes to other boards then followed. He then selected loyalists like Trump's 2016 presidential campaign manager Corey Lewandowski and deputy campaign manager David Bossie to fill the vacancies.

Some of the loyal individuals the administration sought to install on the boards included people who have been surrounded by controversy.

Scott O'Grady, a retired US Air Force F-16 pilot, was appointed to the Defense Policy Board in December. The war hero promoted several conspiracy theories in support of Trump's baseless claims that the presidential election was stolen.

O'Grady recently shared a tweet saying that " suggesting that martial law is not a bad idea when there is an attempted coup against the president," according to CNN, which also reported that O'Grady shared other debunked theories about the election, insulted former military officials, and retweeted at least one pro-QAnon hashtag.

Ret. US Army Gen. Anthony Tata, who was also appointed as an advisor, previously drew criticism for his characterization of former President Barack Obama as a "terrorist leader" with "Islamic roots."

As the Trump administration quickly moved to overhaul the advisory boards, an advisor on the Defense Business Board who survived the purge resigned in protest. In his resignation letter, Steve Blank wrote that by purging advisory boards and filling them with Trump allies, the Trump administration had "put the nation's safety and security at risk."

Speaking to the press Tuesday, Pentagon spokesman John Kirby told reporters that the "frenetic activity" at the end of the Trump administration "deeply concerned" Austin and was a driving factor in his decision to clean out the boards and start over.