New York Times:

After an extensive inquiry, American investigators concluded that the attack in Ukraine on Dec. 23 may well have been the first power blackout triggered by a cyberattack — a circumstance many have long predicted. Working remotely, the attackers conducted “extensive reconnaissance” of the power system’s networks, stole the credentials of system operators and learned how to switch off the breakers, plunging more than 225,000 Ukrainians into darkness.

In interviews, American officials said they have not completed their inquiry into who was responsible for the attack. But Ukrainian officials have blamed the Russians, saying it was part of the effort to intimidate the country’s political leaders by showing they could switch off the lights at any time.

Wow.