Updated at 10:50 a.m. Aug. 17 with reaction from President Donald J. Trump.

AUSTIN — Admiral William H. McRaven literally wrote the book on black ops. He led the team that brought down Osama bin Laden and questioned outmoded concepts of sexual assault in the military and at his alma mater in Austin.

Now, he's challenging the leader of the free world. On Thursday, just hours after the news that ex-CIA director and frequent President Donald Trump critic John Brennan's security clearance had been revoked, McRaven had a message for the president:

"Revoke my security clearance, too."

In an op-ed for The Washington Post, McRaven praised Brennan as "a man of unparalleled integrity" and maligned the president for what he called Trump's "McCarthy-era tactics" to "suppress the voice of criticism."

"Like most Americans, I had hoped that when you became president, you would rise to the occasion and become the leader this great nation needs," McRaven wrote. "Your leadership, however, has shown little of these qualities. Through your actions, you have embarrassed us in the eyes of our children, humiliated us on the world stage and, worst of all, divided us as a nation."

McRaven requested that the president revoke his clearance, which many top-level public servants retain after their retirement, "so I can add my name to the list of men and women who have spoken up against your presidency."

On Friday, Trump reacted to the request, saying, "I don't know McRaven. I know that I've gotten tremendous response from having done that because security clearances are very important to me. Very, very important."

Brennan responded to Trump's decision to rescind his clearance on Thursday, accusing the president of making a "desperate" move "to protect himself" and describing Trump's claims that there has been no collusion between the Trump campaign and Russia as "hogwash" in an op-ed for The New York Times.

McRaven, like Brennan, has long been an outspoken critic of Trump. A former college newspaper reporter, the special operations commander has called Trump's attacks on the press the "greatest threat to democracy" in his lifetime. He opposed then-candidate Trump's campaign pledges to restrict travel by Muslims to the United States and questioned whether the president was making the right calls in civil war-torn Syria.

In Texas, his position as head of the University of Texas System also required him to become deeply involved in state politics. During his three-plus years as chancellor, McRaven supported in-state tuition for students regardless of citizenship status and opposed allowing concealed weapons on college campuses.

As Baylor University and other schools dealt with backlash over their handling of campus rape, McRaven tapped into UT's faculty expertise and his experiences in the military to craft and implement a systemwide sexual assault survey. The results showed that 15 percent of female undergraduate students said they had been raped.

McRaven also butted heads with state lawmakers and Gov. Greg Abbott in his final year over his — largely secret — plans to extend UT's footprint in Houston. The plan was eventually scuttled and led to questions about how much longer his tenure at the system would last.

The son of an Air Force colonel, McRaven was shuttled around all over the world before the family settled in San Antonio when he was in high school. McRaven graduated with a journalism degree from the University of Texas at Austin, after which he attended the Naval Postgraduate School, where his 600-plus page thesis helped map out the military's future strategy for special operations.

He rose through the ranks of the Navy to eventually head of U.S. Special Operations Command. In 2011, he organized and executed Operation Neptune Spear, a Navy SEAL raid that resulted in the death of bin Laden. He ended his long career of military service three years later to become UT system chancellor.

He resigned earlier this year due to health concerns but is reportedly joining UT's Lyndon B. Johnson School of Public Affairs as professor of national security.

Washington Bureau Chief Todd J. Gillman contributed to this report.