The global outbreak of NotPetya malware on 27 June 2017 hitting multiple organisations in Ukraine, Europe, US and possibly Russia can most likely be attributed to a state actor, concluded a group of NATO CCD COE researchers Bernhards Blumbergs, Tomáš Minárik, LTC Kris van der Meij and Lauri Lindström. Analysis of both recent large-scale campaigns WannaCry and NotPetya raises questions about possible response options of affected states and the international community. 

https://ccdcoe.org/notpetya-and-wannacry-call-joint-response-international-community.html