https://www.reuters.com/article/us-usa-cyber-nsa/russian-hackers-stole-u-s-cyber-secrets-from-nsa-wsj-idUSKBN1CA2DO

Russian government-backed hackers stole highly classified U.S. cyber secrets in 2015 from the National Security Agency after a contractor put information on his home computer, the Wall Street Journal reported on Thursday, citing unnamed sources.