Power stations and other critical infrastructure are being targeted for attacks at an increasing clip across the United States, leaving energy and extremism experts worried about what a potential coordinated assault against the Texas grid might look like. Earlier this week, federal authorities announced the arrests of two members of the neo-Nazi group Atomwaffen Division, accusing them of planning a series of sniper attacks intended to devastate Maryland’s electric grid. In December, power stations in North Carolina were targeted by shootings, leaving 45,000 homes and businesses without power for days. Last year, the Department of Energy reported 25 instances of...