WASHINGTON — The electric grid, as government and private experts describe it, is the glass jaw of American industry. If an adversary lands a knockout blow, they fear, it could black out vast areas of the continent for weeks; interrupt supplies of water, gasoline, diesel fuel and fresh food; shut down communications; and create disruptions of a scale that was only hinted at by Hurricane Sandy and the attacks of Sept. 11. ~ SNIP ~ One goal of the drill, called "GridEx II", is to explore how governments would react as the loss of the grid crippled the supply chain...