A government video shows the potential destruction caused by hackers seizing control of a crucial part of the U.S. electrical grid

The video, produced for the Homeland Security Department and obtained by The Associated Press on Wednesday, was marked "Official Use Only." It shows commands quietly triggered by simulated hackers having such a violent reaction that the enormous turbine shudders as pieces fly apart and it belches black-and-white smoke

Vice President Dick Cheney is among those who have watched the video

The video was produced for top U.S. policy makers by the Idaho National Laboratory

"They've taken a theoretical attack and

shown

the impact you can have using cyber means and cyber techniques

said Amit Yoran, former U.S. cybersecurity chief for the Bush administration

executive for NetWitness Corp., which sells

network monitoring software.

There was no evidence any U.S. utility company suffered damage from hackers or terrorists using this technique