Colleagues of an American student from Princeton University who was jailed in Iran on spying charges expressed shock on Monday, calling him a gifted and innocent history scholar whose ordeal has traumatized his family and community.

Academics and Iran experts said the arrest and punishment of the student, Xiyue Wang, first announced Sunday in Iran, may chill scholarly ties between the United States and Iran, subverting promises of more openness from its president, Hassan Rouhani.

“This kind of situation makes me wake up in a cold sweat,” said Bruce Carruthers, the director of the Buffett Institute for Global Studies at Northwestern University in Evanston, Ill. “It is a deeply worrisome event, and I hope to God that it is not a trend or harbinger of things to come.”

Despite the history of hostility between the United States and Iran, scholarly exchanges have survived. But Mr. Wang’s case, Mr. Carruthers said, shows that “a visitor like that can be a bargaining chip.”