A drumbeat of suspensions of top Pentagon officials continued into a second day on Wednesday with a defense official confirming that Colin Carroll, the chief of staff to the deputy defense secretary, was suspended.

Carroll is the third top political appointee to be suspended from his job in connection with a leak probe -- apparently into a news story about a proposed top secret China briefing to Elon Musk -- that also ensnared Dan Caldwell, a top adviser to Defense Secretary Pete Hegseth, and Darin Selnick, Hegseth's deputy chief of staff.

The move has surprised and puzzled officials in the Pentagon since Caldwell and Selnick were trusted advisers who were close to Hegseth.

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Earlier Wednesday, Axios reported that both Caldwell and Selnick were being investigated^[2] as part of a probe into who told The New York Times about plans for the Pentagon to provide a top-secret briefing on China to Musk, the world's richest man who has been empowered by President Donald Trump to dramatically slash and reshape the federal government.

The original news story of the planned China briefing, which was published more than a month ago^[3], said that the Pentagon had scheduled a briefing for the billionaire on the U.S. military's plan for any war that might break out with China. It cited two officials as the sources for that news and two others who confirmed broader details.

Reporters asked Hegseth about the firings on Wednesday during the open portion of his meeting with El Salvador's defense minister, but they went unanswered.

Prior to coming to the Pentagon in January, Carroll worked at the defense contractor Anduril Industries, according to his LinkedIn profile^[4]. He also worked at the Pentagon's Joint Artificial Intelligence Center as its chief operating officer under the Biden administration but, according to Politico^[5], he was fired for creating a hostile work environment.

Meanwhile, both Caldwell and Selnick were close allies of Hegseth. Both men worked at the same nonprofit -- Concerned Veterans for America -- and Caldwell even worked there when Hegseth was running the organization.

At the Pentagon, both men were given major roles in the three months since Trump returned to office.

By late March, Caldwell was designated as Hegseth's point person for top national security officials and the vice president, according to the defense secretary's unsecured conversation in a Signal app group chat^[6] with other top administration officials -- which mistakenly included the editor of The Atlantic -- about plans for military strikes against Houthi rebels in Yemen.

One defense official, who was granted anonymity by Military.com to speak candidly, even described Caldwell as being like a family member to Hegseth.

Meanwhile, Selnick was one of the first Trump officials to come^[7] to the Pentagon, and he took over running its personnel and readiness directorate, which fielded the slew of directives and orders to address the plans to oust transgender troops^[8], offer back pay to COVID-19 vaccine refusers^[9] and address standards among the force^[10].

Selnick was recently promoted from that position to be Hegseth's deputy chief of staff.

Military.com reached out to both Caldwell and Selnick but did not receive any replies.

The fallout from the alleged leak investigation is not the first shake-up of staff in the top offices of the Pentagon.

Last month, Hegseth's office also sidelined another senior political appointee, John Ullyot, who had acted as the top Pentagon spokesman before Sean Parnell took over the role.

Ullyot's reassignment came after he issued an especially blistering statement defending the removal of an online article honoring trailblazing Black baseball player and Army^[11] veteran Jackie Robinson.

Ullyot issued two statements on the matter in which he argued that Hegseth's staff did not view or highlight Robinson -- along with other female service members and troops with minority backgrounds who were censored from Defense Department media -- "through the prism of immutable characteristics, such as race, ethnicity, or sex."

Robinson is a historic figure in baseball because he was the first Black player to play in the major leagues in the 1940s, during a time of segregation and systemic racism in the U.S.

In a video posted days after Ullyot's ousting, Parnell largely reiterated Ullyot's message^[12] but admitted that "some important content was inadvertently pulled offline" and blamed artificial intelligence tools "and other software."

He also alleged that content was being both "mistakenly removed" and "maliciously removed." But the Defense Department also censored much more media on female, minority and LGBTQ+ troops that has not been restored, and has undertaken a wider campaign to ban books^[13] from military libraries, including^[14] the U.S. Naval Academy^[15].

-- Patricia Kime contributed to this report.

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A dozen students at Defense Department grade schools across the globe are suing the department after books were removed from libraries, school yearbooks were allegedly censored, and class curriculums were sanitized to implement President Donald Trump's anti-diversity and anti-LGBTQ+ executive orders.

Alleging First Amendment violations, the American Civil Liberties Union filed a federal lawsuit Tuesday evening against the Department of Defense Education Activity and the Pentagon on behalf of 12 students in pre-K through 11th grade from six military families who attend schools on bases in Virginia, Kentucky, Italy and Japan.

"The implementation of these EOs, without any due process or parental or professional input, is a violation of our children's right to access information that prevents them from learning about their own histories, bodies and identities," Natalie Tolley, a parent from one of the military families suing, said in a statement released by the ACLU. "I have three daughters, and they, like all children, deserve access to books that both mirror their own life experiences and that act as windows that expose them to greater diversity. The administration has now made that verboten in DoDEA schools."

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A DoDEA spokesperson declined to comment on the lawsuit Wednesday, saying that "as a matter of policy, the DoDEA does not comment on ongoing litigation."

Among his first acts in office, Trump ordered every federal agency to get rid of all policies and materials related to "gender ideology," a right-wing term for being transgender, and the ill-defined concept of "diversity, equity and inclusion."

In practice, at the Pentagon, those orders have resulted in the erasure of minorities^[2], women and LGBTQ+ people from public websites and databases; restrictions on what soldiers can write^[3] in academic papers; and the elimination of advisory groups^[4] seeking to improve troops' quality of life, among other effects. Some actions, such the removal of webpages about Navajo Code Talkers^[5] and Jackie Robinson^[6], were reversed after public outrage.

At DoDEA schools, books have been pulled from school libraries ranging from classics such as "To Kill a Mockingbird," to a picture biography about the late Supreme Court Justice Ruth Bader Ginsburg, to an award-winning fiction novel about a transgender teen participating in a national debate competition, to Vice President JD Vance's own memoir "Hillbilly Elegy," according to the lawsuit.

Class curriculums have also been sterilized to remove content the administration objects to, according to the lawsuit. In addition to the widely reported elimination of gender and sexuality chapters from Advanced Placement Psychology textbooks, the lawsuit also alleges that textbooks for health classes have been censored.

Chapters that have been cut from health class textbooks include: "Communicable Diseases: Sexually Transmitted Diseases;" "Unwanted Sexual Activity: Sexual Harassment;" "Human Reproductive System, Menstrual Cycle, and Fetal Development;" "Abuse and Neglect;" and "Adolescence and Puberty," according to the suit.

Middle school health classes also are no longer teaching a chapter called "What Is Sexuality?" that "simply defines terms, accurately and without bias, that are commonly used in everyday conversation," the lawsuit says.

Student yearbooks have also been instructed not to include "any visual depictions, written content or editorial choices that would directly or indirectly support the instruction, advancement, and/or promotion of 'gender ideology' and/or 'social transition,'" according to the lawsuit.

And, in line with a Defense Department memo declaring "identity months dead," Black History Month assemblies and Women's History Month events were banned, the lawsuit says. While "host nation engagement" events are allowed, the lawsuit calls that distinction "nonsensical," citing the fact that a Guam History and Chamorro Heritage Day celebration was allowed under that category despite the fact that Guam is a U.S. territory and not a host nation.

"Students in DoDEA schools, though they are members of military families, have the same First Amendment rights as all students," Emerson Sykes, senior staff attorney with the ACLU's Speech, Privacy and Technology Project, said in a statement. "Like everyone else, they deserve classrooms where they are free to read, speak and learn about themselves, their neighbors and the world around them."

DoDEA's implementation of Trump's orders has sparked a level of pushback not typically seen publicly from military families.

In addition to the lawsuit, hundreds of DoDEA students have participated in walkouts^[7] despite the threat of punishment from school administrators and Pentagon officials. Military family members also protested^[8] when Defense Secretary Pete Hegseth visited a base in Germany in February.

Meanwhile, Trump administration book bans at Pentagon institutions have not been isolated to the DoDEA.

The Naval Academy^[9] recently pulled nearly 400 books^[10] from its libraries, including books about the Holocaust and Maya Angelou's acclaimed autobiography, "I Know Why the Caged Bird Sings."

The Associated Press reported Tuesday that the libraries^[11] at West Point^[12] and the Air Force Academy^[13] have also been directed to review their collections for any books to remove.

Related: Banned Books, School Walkouts, Child Care Shortages: Military Families Confront Pentagon's Shifting Rules^[14]