An Iranian researcher may not be able to assist a Duke University project to help paralyzed people walk again because of President Donald Trump’s order halting travel to the U.S. from several predominantly Muslim countries.

Mehdi Ordikhani Seyedlar was supposed to start work in May at Duke’s Center for Neuroengineering on research that is developing exoskeletons for paralyzed people that they can control with their mental power.

“I think I can use my skills to really serve people in the United States. This is something that I was really intending to do. I still hope to do so,” Seyedlar said via Skype from his home in Denmark.

Seyedlar’s situation isn’t unique, and the Association of American Universities has issued a statement condemning Trump’s order and calling for a quick end to it.

The association says it recognizes the importance of a strong visa process to national security, but barring the entry or return of individuals from certain countries is already causing damage, has stranded students who have been approved to study here and are trying to get back to campus, and threatens to disrupt the education and research of many others.

“Causing such kinds of limitations for ordinary people is just not fair,” Seyedlar said.

Michael Schoenfeld, Duke’s vice president for public affairs and government relations, called Trump’s order disturbing.

“We have people coming from all over the world who want to experience American education. It is one of the things that is the crown jewels of this country,” Schoenfeld said. “It’s based on the free transit of students and scholars. If you take that away, you make the country a less attractive place, you make the country a less successful place, you make the world a less successful place, and that is the greatest shame in all of this.”