Nationwide blackout?

With 20 minutes & enough rifles, a crew could potentially turn the lights out nationwide as reported by the New York Times: A blackout caused by lost transformers could last 18 months or longer.
The Federal Energy Regulatory Commission is responsible for ensuring the reliability of the electrical grid. It analyzed the cascading effects of knocking out the most critical substations in each of America's interconnections, where multiple high-voltage lines came together. “We came up with some very astounding numbers,” FERC chair Wellinghoff said. “If you knock out 9 total substations in those 3 grids (Western, Eastern, & Texas), you can black out _all_ the US.” Per Wellinghoff, which 9 substations were taken offline didn’t matter as long as each one was among the 10 most important in its region.
Since 2021, the average wait time for a large power transformer — the kind you’d find at a major substation, capable of handling tens or hundreds of thousands of volts — has climbed from less than a year to 128 weeks, with some lead times growing as long as five years. “The transformer shortage is bad,” Ajey Pandey, an energy analyst & a former municipal resource planner, told ChinaTalk, a tech-focused media outlet. “It’s like hair-on-fire, biting-my-nails, losing-sleep levels of bad.”
Watergate felon and former FBI agent G. Gordon Liddy used the concept in his Jan. 1989 OMNI story "RULES OF THE GAME" so this is not an unknown concept among possible disasters.