The US administration has said North Korea was “directly responsible” for the WannaCry malware attack affecting hospitals, businesses and banks across the world earlier this year, the BBC reports.
The attack is said to have hit more than 300,000 computers in 150 nations, causing billions of dollars of damage.
Thomas Bossert, an aide to US President Donald Trump, made the accusation in the Wall Street Journal newspaper.
It is the first time the US has blamed the country officially for the worm.
Mr Bossert, who advises the president on homeland security, said the allegation was “based on evidence”.