In July, concerned about what he called an “increasingly unpredictable and uncertain” immigration process, Harvard University president Lawrence Bacow penned a curt letter to two top Trump administration officials, Secretary of State Mike Pompeo and Acting Homeland Security Secretary Kevin McAleenan.

“Students report difficulties getting initial visas — from delays to denials,” Bacow wrote in the letter. “Scholars have experienced postponements and disruptions for what have previously been routine immigra­tion processes such as family visas, renewals of status, or clearance for international travel.”

About a month later, incoming Harvard freshman Ismail B. Ajjawi, a 17-year-old Palestinian from Lebanon, was detained by U.S. Customs and Border Protection (CBP) at a Boston airport. The story went viral when Ismail, according to the Harvard Crimson, was denied entry after he said CBP officers dug up some friends’ social media posts that were critical of the U.S. Ismail has since been allowed to enter the country, a CBP spokesperson confirmed to Teen Vogue, and was granted an F-1 student visa. He arrived on campus 10 days after initially being turned away by CBP.

The controversy attracted fresh scrutiny to the plight of international students in Trump’s America, as new policies and directives over the past few years have left many student immigrants confused about what the changes mean for them. These kinds of incidents aren’t random: The approval of student visas is down, and visas in limbo are heavily backlogged, according to government data and immigration experts. Although State Department officials claim they continue to prioritize international students, there are some in higher education and immigration law who say the process seems to have gotten harder.

On the heels of the Harvard incident, nine Arizona State University (ASU) students from China were detained by CBP officials, without apparent explanation, at a Los Angeles airport. The students were forced to return to China, according to a university press release, despite being “academically eligible to return to ASU and to the United States under their visas.”

“The experience of our nine students seems to be mirrored by the experience of the Harvard University student,” ASU president Michael Crow wrote on August 29 in a letter also addressed to Pompeo and McAleenan. Crow may have been referencing a CBP directive signed in 2018 when he castigated the administration’s new “standard procedures” for screening international students. He demanded a better explanation of the latest rules.

In a written statement to Teen Vogue, a CBP spokesperson said the students “were deemed inadmissible to the United States based on information discovered during the CBP inspection.” The spokesperson would not elaborate on what information made the students inadmissible.

“[I]t is beyond my comprehension how the U.S. government could establish and implement policies that bring about the outcomes we are now witnessing,” Crow wrote in his letter. It is unclear whether the students will be allowed back into the U.S. at any point this semester to continue their studies in person.

“[I]t is concerning to see an incident like [Ismail’s], let alone seeing another similar incident involving nine Arizona State students right after,” Dr. Hironao Okahana, associate vice president of policy and research analysis at the Council of Graduate Schools, told Teen Vogue. “[W]e’ll be carefully observing to see if any additional incidents occur as quarter-system schools begin their term in a few weeks.”

Okahana said he’s heard reports of worries over two types of slowdowns in processing times: one has to do with visa applications and another with applications that permit students to stay in the U.S. after graduation to gain relevant work experience. Additional instances of “graduate students, scholars, or faculty members being unexpectedly denied entry into the United States” have been reported as well, he said.