Temp.Isotope has been implicated in cyber activity targeting the 2019 Ukrainian election and a previous campaign against U.S. energy companies.

NotPetya cost a reported $1 billion to a collection of U.S. organizations, officials said.

It's the latest milestone in a case that spans at least four countries. French and U.S. prosecutors allege the Russian helped create the infamous Locky ransomware and then launder the resulting bitcoin ransom payments.

"[W]e’ve seen increased attention on the threats posed by APTs in the context of the U.S. election," Google's Shane Huntley said.

"This is a very serious incident, affecting our most important democratic institution,” Norway's foreign minister said.

The discovery adds to a growing body of public reporting on corporate hacking that has often focused on Chinese-speaking hackers