Harvard University on Thursday filed a legal challenge to President Donald Trump’s efforts to block visas for foreign students planning to attend the Ivy League college.“Singling out our institution for its enrollment of international students and its collaboration with other educational institutions around the world is yet another illegal step taken by the Administration to retaliate against Harvard,

On Wednesday, President Donald Trump signed a directive seeking to block U.S. entry for Harvard’s international students. It marked the administration’s latest effort to squeeze Harvard’s foreign enrollment after a federal judge in Boston blocked the withdrawal of its certification to host students from overseas.

The president had issued a proclamation targeting international students who seek to enroll at Harvard. The moves escalated a legal battle between the two parties.