Hackers' threats
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Sony hack: White House views attack as security issue

A cyber attack on Sony Pictures that forced the cancellation of a major film release is being seen as a serious national security matter, the US says.

A White House spokesman said the US believed the hacking was the work of a "sophisticated actor" - but refused to confirm if North Korea was responsible.

Sony withdrew The Interview, a new comedy film about North Korea's leader, after threats from hackers.

Hackers have already released sensitive information stored on Sony computers.

Jon Sopel reports.

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