If you give 50 engineers the task to come up with ideas for breaking a countries infrastructure on a budget I'm pretty sure 45 of them will go for the electricity plants and will look for the most vulnerable place to cause a dead short in a high voltage circuit. There aren't that many of them, they're our Achilles heel. I'm not at all surprised that the military has taken this idea into their arsenal.
I remember reading somewhere that in Total War scenarios you should poison the water source if you are not able to capture and control it. I think it was Art of War by Sun Tzu.
