Sony chief executive Kazuo Hirai said that both former and current employees at its movie studio were victims of "one of the most vicious and malicious cyber attacks that we have known", in his first public comments on November's hack.
Opening a press conference at the International Consumer Electronics Show in Las Vegas, Mr Hirai said he was "very proud" of employees and partners of Sony Pictures who had stood up against the hackers' "extortionist efforts" and worked "literally 24 hours a day, sometimes for days on end", to release The Interview online after North American cinema chains boycotted the film in the face of threats of violence.
"I have to say that freedom of speech, freedom of expression, freedom of association, these are very important lifebloods, lifelines of Sony and our entertainment business," he said.
The Federal Bureau of Investigation said that it had found evidence linking the North Koreans to the cyber attack, after The Interview parodied the country's leader Kim Jong Un. North Korea has denied the charge, describing fresh US sanctions imposed on its agencies and officials linked to its arm trading and intelligence establishment as hostile and repressive.