[cogman10]

Power doesn't work like that.

If someone attacked all the interconnects then the net importers would lose power or brown out while the net exporters would be just fine. (assuming the net importers are currently running power generation at capacity).

For the grids under load, if more capacity can't be brought online they'd do rolling blackouts while working to restore the interconnects.

There are far better targets for a coordinated terrorist attack if they wanted a larger impact.

[thsksbd]

Not necessarily. The sudden loss of load would cause over voltage and frequency ramp ups that cause further trips.

I believe the 2003 blackout was basically a cascading set of load loss faults