The US Government does stuff like this to other countries all. the. time.

We don't hear about it much. But if this is an "act of war" the US has conducted dozens of these kinds of "attacks" on others over the last ten or fifteen years.

Countdown to Zero Day: Stuxnet and the Launch of the World's First Digital Weapon [0]

[0]: https://www.amazon.com/Countdown-Zero-Day-Stuxnet-Digital-eb...

Seems like a good time to plug an excellent book:

Countdown to Zero Day: Stuxnet and the Launch of the World's First Digital Weapon [0]

The US Government has spent two decades and hundreds of millions of dollars building tools to undermine the security of systems around the world, and withholding information from "Industry" that would help harden those systems.

I have no idea who "did" this, I don't really care. The NSA has been loading this footgun for decades.

[0] https://www.amazon.com/Countdown-Zero-Day-Stuxnet-Digital-eb...

Somewhat related, but the book Countdown to Zero Day is about both the Stuxnet worm and the potential for digital attacks on infrastructure. Very good read and intro to the topic. https://www.amazon.com/dp/B00KEPLC08/