The United States National Security Agency says hacking the country’s infrastructure is a "matter of when, not if."
The notorious agency’s chief, Admiral Michael Rogers, made the remarks while speaking at the RSA cyber security conference in San Francisco on Tuesday, Reuters reported.
Rogers referred to a recent hack on Ukraine's power grid, voicing concerns.
The Ukraine blackout that affected some 225,000 in December 2015 was the outcome of a cyber attack, according to the US government.
Some researchers believe the move is linked to a Russian hacking group known as “Sandworm."
US has on different occasions threatened China as well for its so-celled cyber espionage.
Last December, the two geopolitical rivals reached an agreement to expand cooperation on stopping cyber espionage.
The US government says Chinese government entities were behind the massive data breach of the Office of Personnel Management (OPM) in 2014, targeting the records of 22 million federal workers.
The NSA’s widespread surveillance of Americans and foreign nationals, as well as political leaders around the world, was exposed by former contractor Edward Snowden in 2013.
Snowden, who lives in Russia where he has been granted asylum, has said that US government surveillance methods far surpass those of an ‘Orwellian’ state, referring to George Orwell’s classic novel “1984,” which describes a society where personal privacy is continuously invaded by spy agencies.