Hackers are throwing references to Shakespeare in code being used to target the country's wind industry.
The simulation also included officials from throughout the U.S. government and from allied partners to emphasize stronger coordination.
Researchers say that the same sophisticated group behind last year's incident in Saudi Arabia has attacked multiple U.S. companies.
As foreign hackers continue to probe the U.S. grid for weaknesses, a cyber exercise for the North American energy sector has shown that many utility personnel still lack access to the classified information needed to stay on top of the threat.
Schneider Electric had remained largely silent about an August incident where Trisis shut down operations at a Saudi energy plant.
What researchers found has been described to CyberScoop as a tool so dangerous that its mere existence significantly intensifies the global digital arms race.