President Donald Trump signed a proclamation to suspend international visas for new students at Harvard University, the White House announced Wednesday, in a dramatic escalation of its efforts to block foreign nationals from enrolling at the elite university. The proclamation temporarily blocks the entry of nearly all new Harvard student as nonimmigrants into the United States under visas most international students use to study at universities or participate in academic exchange programs in the country. It also directs the Secretary of State "to consider revoking" those visas – known as F, M and J visas – for current Harvard students who meet the proclamation's "criteria," the White House said in a statement on Wednesday. The move throws Harvard's ability to enroll international students – which make up about 27% of the student body – into doubt once again just days after a federal judge blockedthe administration's last attempttargeting foreign students at the nation's oldest and wealthiest university. A Harvard spokesperson said the university will "will continue to protect its international students." "This is yet another illegal retaliatory step taken by the Administration in violation of Harvard's First Amendment rights," the university spokesperson said in a statement to CNN. The White House said the latest move is an attempt to "safeguard national security," accusing Harvard of having "concerning foreign ties and radicalism." The announcement also cited the university's alleged failure to "provide sufficient information" about foreign students and "reporting deficient data on only three students." "Harvard is either not fully reporting its disciplinary records for foreign students or is not seriously policing its foreign students," the White House said. It also accused the Ivy League of failing to address antisemitism on campus as well as its persistence in "prioritizing" diversity, equity, and inclusion (DEI). The new proclamation "exempts aliens whose entry is deemed in the national interest" and does not apply to aliens attending other US universities through the SEVP program. The president's order is scheduled to last six months unless extended, according to the proclamation, which gives the Attorney General and the Secretary of Homeland Security 90 days to make a recommendation on whether it should be extended. "Harvard's conduct has rendered it an unsuitable destination for foreign students and researchers," the proclamation reads. The move comes after US District Court Judge Allison Burroughs last week ordered the Trump administration to not make any changes to Harvard's international student visa program indefinitely. The order came days after the judgetemporarily halted the administration's revocationof the university's ability to enroll foreign students. The court proceedings stemmed from a directive from Homeland Security Secretary Kristi Noem to her agency, ordering the termination of Harvard's Student and Exchange Visitor Program (SEVP) certification, citing the university's refusal toturn over the conduct recordsof foreign students requested by the DHS in April. Harvard has accused the government of failing to follow its own requirements for removing a university from the SEVP program and argued the revocation was "clear retaliation" for its refusal of the government's ideologically rooted policy demands. Harvard and Trump officials havebeen locked in conflictfor months as the administration demands the university make changes to campus programming, policies, hiring and admissions to root out on-campus antisemitism and eliminate what it calls "racist 'diversity, equity and inclusion' practices." The US Department of Education haswarnedUS colleges and universities ofpossible consequencesif they don't take adequate steps to protect Jewish students and separatelythreatened federal fundingof any American academic institution that considers race in most aspects of student life. The administration also escalated its fight with Columbia University on Wednesday, declaring the school doesn't meetaccreditation standardsbecause of its failure to protect Jewish students. The White House has homed in on foreign students and staff it believes participated in contentious campus protests over the Israel-Hamas war. The administration's attacks on Harvard began March 31, when Trump officials sent Harvard a letter advising they wouldreviewall roughly $9 billion of the Ivy League institution's contracts and grants. Harvard sued the Trump administration over itsfreezing of $2.2 billionin federal funding after the university wouldn't agree to policy changes demanded by the White House. The White House later cutanother $450 million in grants, and the president has threatened to revokeHarvard's tax-exempt status. Last week, the White House directed federal agencies to cancelall remaining contracts with HarvardUniversity – about $100 million in all, two senior Trump administration officials told CNN. Some Harvard staff worry draining the university of its foreign students would debilitate the academic prowess of both the institution and, potentially, American academia as a whole. "This retaliatory action threatens serious harm to the Harvard community and our country, and undermines Harvard's academic and research mission," university spokesperson Jason Newton said last month after the administration moved to ban Harvard from enrolling foreign students. In the 2024-2025 academic year, there were6,793 international students enrolledat Harvard, and its international academic population is comprised of 9,970 people, according to the university. International students aremore likely to pay full tuition at US colleges, in part because most aren't eligible for federal financial aid, bringing significant funding to colleges, CNN has reported. More than three-quarters of international students primarily fund their education themselves, through their family or through current employment,the Institute of International Education found. Less than one-fifth received primary funding from their US college or university. This story has been updated with additional details. CNN's Elizabeth Wolfe, Andy Rose, Danya Gainor, Katelyn Polantz and Devan Cole contributed to this report. For more CNN news and newsletters create an account atCNN.com