Even before the terrorist attacks on the World Trade Center and Pentagon, government inspectors had found security to be inadequate at the U.S.’s 103 nuclear plants. From 1991 to 2000, nearly half of the 68 plants tested showed “a potential vulnerability” to terrorists. Now, the U.S. Nuclear Regulatory Commission has reversed claims it made right after the attacks that the plants would be capable of withstanding the impact of commercial airplane crashes. Enviros are criticizing the NRC for continuing to back a self-policing security program by plant operators, rather than imposing a stricter security regime.