US officials believe Chinese hackers may still have access to key US computer networks

(CNN) — US officials believe Chinese hackers could still have access to sensitive US computer networks they’ve targeted in recent months as a top American cyber official told CNN he is concerned about the “scope and scale” of the activity.

The newly revealed Chinese government-backed hacking campaign, which targeted key US sectors like maritime and transportation networks, is “unacceptable” because the hackers sought access to networks that might allow them to disrupt critical services in the future, National Security Agency Director of Cybersecurity Rob Joyce said in an interview on Thursday.