“My point is that now that vulnerability is out there all over China for anybody to take advantage of,” he said.

But specialists in the field of network science, which explores the stability of networks like power grids and the Internet, said that was not the case.

Image Larry M. Wortzel, a military strategist, recently drew attention to the paper. Credit... Ken Cedeno for The New York Times

“Neither the authors of this article, nor any other prior article, has had information on the identity of the power grid components represented as nodes of the network,” Reka Albert, a University of Pennsylvania physicist who has conducted similar studies, said in an e-mail interview. “Thus no practical scenarios of an attack on the real power grid can be derived from such work.”

The issue of Mr. Wang’s paper aside, experts in computer security say there are genuine reasons for American officials to be wary of China, and they generally tend to dismiss disclaimers by China that it has neither the expertise nor the intention to carry out the kind of attacks that bombard American government and computer systems by the thousands every week.

The trouble is that it is so easy to mask the true source of a computer network attack that any retaliation is fraught with uncertainty. This is why a war of words, like the high-pitched one going on these past months between the United States and China, holds special peril, said John Arquilla, director of the Information Operations Center at the Naval Postgraduate School in Monterey, Calif.

“What we know from network science is that dense communications across many different links and many different kinds of links can have effects that are highly unpredictable,” Mr. Arquilla said. Cyberwarfare is in some ways “analogous to the way people think about biological weapons — that once you set loose such a weapon it may be very hard to control where it goes,” he added.