People-to-people exchanges between China and the United States are positive for both sides and should be free of unwarranted restrictions, Gordon H. Chang, professor of American history at Stanford University, said Monday.

"We want to have open exchange, communication, dialogue, so Americans learn about Chinese and Chinese about America," Chang told Xinhua at the end of a seminar on China's influence in the United States held at Stanford University.

He criticized some in the United States for hyping up the so-called "China threat" to the American society. "The rhetoric is getting stronger, and words are powerful, but it doesn't prove anything," said Chang, whose study focuses on modern China and international security.

"When you start to make old speculation, innuendo, it really worsens the situation," he noted.

He said that given the huge Chinese community in the United States, there are people who may do wrong, "but I don't think that characterizes the situation for Chinese in the United States."

Chang said some people fear an increasingly powerful China and exaggerate fears about the Asian country's influence on the American society.

He criticized a policy announced by the US government last June to shorten the length of visas for some Chinese students, describing it as "self-defeating."

"I think open exchange in our relationship is positive to both sides," he said. "We both learn from each other."