Nuclear plants eyed for damage

A senior federal official, who spoke on the condition of anonymity, said the United States was using spy satellites and other means to try to monitor the sprawling nuclear plants. "There appear to be no immediate concerns," the official said.

Nonetheless, "it's potentially a serious issue," Hans Kristensen, a nuclear arms expert at the Federation of American Scientists, a private group in Washington, said in an interview. "Radioactive materials could be released if there's damage."

China began building the plants in the 1960s, figuring that their remote locations would make them less vulnerable to enemy attack.