President Donald Trump said Wednesday that he will deny visas for foreign students trying to come to the U.S. to attend Harvard University, his latest attack on the prominent Ivy League college.

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 Trump administration has sought a workaround to the courts, which have largely blocked his efforts to restrict foreign students.