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 foreigners from enrolling at the elite university.

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.

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.