International applicants for a prestigious Dartmouth engineering program dropped 30 percent this year, startling the dean of a school long accustomed to growth in demand from overseas. His colleagues at other top schools told him they were seeing danger signs as well, as they anxiously monitor whether the sharp turn in U.S. immigration and travel policies under President Trump will keep foreign scholars away.

“I totally agree that we need to vet people, we need to be careful. It makes sense to take a close look at people applying to come to the U.S.,” said Terrie Fox Wetle, dean of public health at Brown University. “But when you begin to send a message that you don’t welcome good people … it has a chilling effect.”

Wetle said she had just attended a conference at which other deans were talking about international students who retracted their acceptance of offers of admission. She herself has heard a lot of anxiety from international students. “They’re afraid to come.”...

... Joseph Helble, dean of engineering at Dartmouth, said colleagues from 19 other schools told him recently of unusual drops in overseas applications — a surprising development for a field that ordinarily draws intense global demand. The declines for various types of programs were mostly in the range of 10 percent to 30 percent, akin to the 30 percent decline in international applications for Dartmouth’s program in engineering management.

Helble said he and his colleagues are worried about slowing technological innovation. “I’m a sports fan,” he said. “When you field a sports team, you want to put the best possible team on the field and see how they compete against the best possible competition. We want them all to have the opportunity to collaborate with the best and the brightest; that’s how you move the best technology from the lab to the marketplace.”