The Nuclear Regulatory Commission is beefing up security at commercial nuclear power plants, including more stringent requirements to counter potential cyber attacks. The NRC issued regulations calling for new training and qualification requirements for security officials and requires plant operators to produce new response strategies in case of the loss of part of a plant because of an explosion or fire. Nuclear watchdog groups have criticized the new rules as falling short of what's needed. They said the NRC still is not addressing full terrorist threats from aircraft, or from a determined, well-armed band of attackers. The NRC also rejected a demand by one group that operators post an armed guard at each entrance to a controlled area of a plant.