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.

President Trump issued a full travel ban from 12 nations and partially restricted entry from seven others, into the United States. The restrictions are scheduled to go into effect on June 9.

The ban, which fully or partially affects nationals from 19 countries, could have ‘devastating consequences,’ experts say.