Students could bypass the United States for friendlier countries as the Trump administration attacks universities and revokes visas. Their loss could hurt schools and the economy.

Xiaofeng Wan, a former admissions officer at Amherst College, now works as a private consultant to international students who want to come to the United States. This week, as he held meetings in China with prospective students, he sensed a deep uncertainty among their parents.

“They really don’t know whether they should send their children to a country where they don’t welcome Chinese students or they see China as a hostile competitor,” Dr. Wan said by telephone from Beijing. “It’s an unprecedented situation that we’ve never seen before.”