According to DHS, the Russians have made inroads into networks with access to critical systems at power plants.  The screen shots that were released by the Department of Homeland Security clearly show that the hackers can manipulate or show down power plants in the United States.

According to Mr. Eric Chien at Symantec, all they need is the political motivation to shut the power off. 

This not new news.  DHS has known about these particular activities 15 months ago. We have been aware of these flaws in our critical infrastructure far longer than that. The Russians ability to exploit our systems at will should prompt the U.S. to kick it into high gear and invest the resources needed to fortify our power systems. While we're at it protect our voting systems as well as anything else we know is at risk!