U.S. helping Ukraine investigate power grid hack

By Dustin Volz and Jim Finkle WASHINGTON (Reuters) - The U.S. Department of Homeland Security said on Tuesday it was helping Ukraine investigate an apparent attack last month on the country's power grid that caused a blackout for 80,000 customers. Experts have widely described the Dec. 23 incident at western Ukraine's Prykarpattyaoblenergo utility as the first known power outage caused by a cyber attack. Ukraine's SBU state security service has blamed Russia for the incident, while U.S. cyber fi