Washington DC - President Donald Trump's administration issued a memo ordering a review of the online activities of all individuals applying for a visa to attend Harvard University.

The State Department instructed US embassies and consulates to begin the process immediately, CNN and Politico reported, citing the memo.

The review affects not only students but also researchers and guest speakers.

The assessment is to include a "complete screening of the online presence" of visa applicants, according to US media reports, citing the directive.

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If an applicant has no online presence or their social media profiles are set to private, consular staff are instructed to assess whether this could indicate evasive behavior and call the applicant's credibility into question.

The latest attack on Harvard is reportedly being treated as a pilot project that could be expanded to other US universities.

It comes after a federal judged blocked the Trump administration from taking away Harvard's ability to enroll foreign students.

Since taking office, the Republican has waged an all out war on universities, where students have been protesting against Israel's US-enabled destruction of Gaza, as well as their schools' role in the carnage.

Under the guise of preventing antisemitism, thousands have had their visas revoked by the State Department, while Trump has stripped universities of vasts amount of federal funding. Opposition to the mass killing of Palestinians has even landed activists in prison.

While most institutions have eagerly restricted their own students' right to protest, Harvard has particularly enraged Trump by refusing to agree to unprecedented government oversight.