At Lakenheath High School, a school for children of U.S. military members in Britain, a club for gay students and their allies can no longer meet. A Women in STEM group has also been placed on hold.
At Ramstein High School in Germany, groups for students of Hispanic and Asian heritage as well as the Pride and Ally club were among those put on pause.
And worldwide, in schools attended by military families, books are under review in response to Trump administration orders cracking down on gender identity and diversity, equity and inclusion.
So far, few U.S. school districts have made sweeping changes in response to Trump administration orders. Most K-12 schools operate largely under local and state control, with limited interference from the federal government.
But a school system run by the Defense Department, which serves about 67,000 students in preschool through high school on military bases around the world, is an exception. As part of the federal government, Defense Department schools have hurried to respond.
In addition to pauses on some affinity clubs related to gender and race and reviews of certain books, Pride decorations have been taken down and Black History Month assemblies and performances have been canceled, according to interviews with students and parents and a copy of a Defense Department memo.
It is a striking change for a school system that has historically been insulated from political fights in education, and whose math and reading scores are routinely among the nation’s best.
Defense schools are global, with locations on some military bases in the United States but also in countries like Belgium and Japan. The student body, like the military itself, is racially and socioeconomically diverse, a history that dates back to the school system’s creation, in part, to serve students of military families in the American South when local schools remained segregated.
“Diversity is, like, the core principle of our schools,” said Kadyn, 16, a junior at Lakenheath High School, northeast of Cambridge, who asked to use only his first name because he is the child of a federal employee.
At his school, he said, “All Are Welcome” signs, which included a rainbow flag and a Black Lives Matter symbol, had been taken down from classrooms. He added that some flags of foreign countries had also been removed. “I feel like we are losing the essence of what makes our schools thrive,” he said.
Will Griffin, a spokesman for Defense Department schools, said that the school system was reviewing its policies to comply with orders from President Trump and his secretary of defense, Pete Hegseth, who called for an end to cultural awareness months, such as those for Black history or women’s history, in his first weeks on the job.
Students have the right to participate in student-led groups, Mr. Griffin said. But student clubs also need a teacher to supervise meetings, and teachers in Defense schools are federal employees subject to the new orders.
It is possible that student affinity groups will be able to start again with employees supervising in an unpaid capacity.
“We will continue to remain focused on providing a rigorous, high-quality educational experience for military-connected students to prepare them for success in college, careers and life,” he said.
In a Feb. 5 memo, Defense officials instructed schools not to use certain materials, including the book “Becoming Nicole,” about the journey of a transgender girl and her family, which was listed as an independent reading novel in sixth through 12th grade. Also listed was a biography of Albert Cashier, a Union Army soldier in the Civil War who was born female but fought and lived as a man, which had been included in some elementary school material.
Material in Advanced Placement Psychology courses concerning gender identity and sexuality was also off limits.
But the orders have also resulted in confusion and uncertainty, as principals and teachers try to interpret guidance and librarians review books in more than 100 schools around the world.
The actress Julianne Moore made headlines when she said that her book “Freckleface Strawberry,” about a 7-year-old girl who dislikes her freckles but learns to embrace her differences, had been pulled for review. “I can’t help but wonder what is so controversial about this picture book,” Ms. Moore, who attended a Defense high school in Frankfurt, wrote on Instagram.
But as of this week, “Freckleface Strawberry” is available for checkout, Mr. Griffin said. He said most books under review were not part of the official curriculum but were extra books available in classrooms or libraries.
“Our principal was saying she was not going to request that the library remove books about Rosa Parks or Dr. Martin Luther King Jr.,” said Allie Allen, the mother of three children who attend Defense schools in Stuttgart, Germany. But a book mentioning Black History Month might be removed, she said.
“There is not a lot of exact guidance,” she said.
Students are also waiting in limbo, said Sophia Carey, 16, a junior at a Defense high school in Germany.
She had wanted to create a girls club at her high school, which would have held an assembly for Women’s History Month, brought in female speakers who work in the military and science and included a community project to offer feminine products in women’s bathrooms at school and in the community.
An obstacle for her club and others, she said, had been finding a teacher who could supervise. “Everything is so uncertain,” she said.
Eric Adelson contributed reporting.
