How else does the CIA know who the terrorists are if not by planning a screening and looking who comes to watch it?

Anyway, it the infrastructure is vulnerable, it's probably a good thing to find out now, before WW3; an unreliable energy infrastructure is the last thing a country at war (they have had a war economy since the 1940s) needs.

In fact, if the CIA doesn't know how many terrorists/freedom fighters it takes to bring down the US energy system and how long, I would say they are the real terrorists, because that's just irresponsible. The only way to play the security game is to know your own vulnerabilities first (and to systematically fix them). So, in this particular case there is a group of people walking around a pipe; that shouldn't be possible to begin with. It is a movie and I don't even live in the US, but that's fairly obvious.

The same holds for the EU with their wind mills at sea. Building a big wind mill costs a million a piece; if a drone could destroy it for 200 times less, perhaps some defense capabilities would have to be installed and perhaps wind as an energy source seizes to be competitive. Or, even more asymmetric, if a submarine drone could just dig for the cables and cut them for less than $100,000, there's no defense against that (the number of submarines in the world times their torpedo capacity is very limited and the length of the cables to defend is very long). Land based solar panels with community batteries are much better from a defense perspective, because no centralized assets are available then to attack for an enemy.