WASHINGTON — President Trump signed an executive order Thursday afternoon protecting freedom of speech on college campuses, surrounded by student activists who have said conservative views are suppressed at universities.

Trump said he was taking “historic action to defend American students and American values that have been under siege.”

More than 100 students joined the president in the East Room for the signing, according to a statement from the White House, along with state legislators and Health and Human Services Secretary Alex Azar and Education Secretary Betsy DeVos. The order directs 12 agencies that make federal grants, in coordination with the Office of Management and Budget, to ensure colleges are complying with the law and their own policies to promote free inquiry and debate.

It does not tie student-aid money to the order.

A senior administration official said Thursday, “Schools are already supposed to be following these rules. And essentially, each agency already conditions grants, and schools are certifying that they’re following these conditions. And they will just add free speech as one of those conditions.”

Trump told the students that people can have their different views, “but they have to let you speak.”

Trump’s announcement earlier this month that he would make federal funding for universities contingent on assurances of free speech elicited cheers and applause at the Conservative Political Action Committee meeting. But it also prompted questions, including who would define and judge free speech, and what type of federal funding could be withheld, research dollars, student aid or both.

Many people following the issue closely said they were relieved the order does not designate or create an agency to police speech on campus.

And many continued to ask questions, saying they won’t know the real impact of the order until they see how it is implemented.

“To the extent that the executive order asks colleges to do what they are either legally required to do — follow the First Amendment, on public campuses — or follow their own promises, on private campuses — we think that should be uncontroversial,” said Robert Shibley, executive director of the Foundation for Individual Rights in Education, which advocates for freedom of speech on campus.

“It will come down to how each agency decides to implement it, what the steps are they take to do that,” Shibley said. His organization and others will watch to see if the agencies are using clearly established First Amendment principles established by the courts or by law, rather than relying on their own interpretation, he said.

Suzanne Nossel, chief executive officer of PEN America, which advocates for free expression, said what’s disturbing about the order is not the language, but the political context. It must be enforced in an ideologically neutral way that upholds the government’s responsibility not to discriminate based on viewpoint. Otherwise there is the risk, she said, “that an order that purports to uphold the First Amendment ends up violating it.”

Ted Mitchell, president of the American Council on Education, which represents college and university presidents, said in a written statement Thursday it remains to be seen how those requirements are fleshed out. “No matter how this order is implemented, it is neither needed nor desirable,” he said, “and could lead to unwanted federal micromanagement of the cutting-edge research that is critical to our nation’s continued vitality and global leadership.”

Spencer Brown, spokesman for the Young America’s Foundation, which advocates for free speech on high school and college campuses, welcomed the order. He said it will build upon decades of efforts by the group, including a 1983 case that went to the Supreme Court after police arrested two Young America’s Foundation protesters outside the Soviet Embassy in Washington who were demonstrating against the Soviet invasion of Afghanistan.

More than a dozen student activists from the group were invited to the White House for the signing ceremony, Brown said. While suppression of certain viewpoints on campus has been a long-running issue, he said it has worsened in recent years.

“I do think we’ve seen a ratcheting-up of the intensity,” he said, in the way conservative students “are treated as second-class citizens on campus. There has been a huge spike in opposition and attempted blocking of our events since Trump was elected president.”

Kristan Hawkins, president of Students for Life of America, which has groups on high school and college campuses in all 50 states that oppose abortion, echoed that idea. “Since the election of President Trump, it’s gotten more dangerous on campus,” Hawkins said. “Those who advocate for legal abortion feel their backs are against the wall. It’s more tense.”

Students have told her about other students — and professors — obstructing their efforts to share their antiabortion views, such as erasing sidewalk chalk messages, throwing blankets over their tables and pulling crosses out of the ground. “They have had to fight for their First Amendment rights,” Hawkins said. “This is an exciting day for us.”

Trump strongly defended free speech on campus two years ago after University of California at Berkeley police canceled a talk by the provocative writer Milo Yiannopoulos when masked activists violently protested the speech, setting fires and throwing stones. Trump tweeted the next morning, “If U.C. Berkeley does not allow free speech and practices violence on innocent people with a different point of view – NO FEDERAL FUNDS?”

Many higher-education leaders have said freedom of speech is central to their academic mission.

“College and university campuses are leading the way for our society in supporting free speech,” said Julie Wollman, president of Widener University in Pennsylvania, in a written statement. On most campuses that work happens daily and naturally, without fanfare, because our overarching and common mission in American higher education is to broadly educate and prepare students for active participation as engaged citizens in our democracy.”

The tensions that make headlines reflect the commitment to honor and encourage free speech, Wollman said.