WASHINGTON: The United States imposed new sanctions on North Korea in retaliation for a cyber attack on Hollywood studio Sony Pictures.

In an executive order, on Friday, President Barack Obama authorised the US Treasury to place on its blacklist three top North Korean intelligence and arms operations, as well as 10 government officials, most of them involved in Pyongyang's arms exports.

Obama said he ordered the sanctions because of “the provocative, destabilising, and repressive actions and policies of the Government of North Korea, including its destructive, coercive cyber-related actions during November and December 2014.”

The activities “constitute a continuing threat to the national security, foreign policy, and economy of the United States”, he added, in a letter to inform congressional leaders.

“The order is not targeted at the people of North Korea, but rather is aimed at the Government of North Korea and its activities that threaten the United States and others,” Obama added.

The sanctions come after hackers penetrated Sony's computers in late November, stealing and releasing over the Internet employee information, unreleased films and an embarrassing trove of emails between top company executives.

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The hackers — a group calling itself Guardians of Peace — then began to issue threats against the company over the looming Christmas release of the comedy film “The Interview”, which depicts a fictional CIA plot to kill North Korea's leader.

The threats led first to worried movie theater owners dropping the film and then Sony cancelling the public debut altogether, before releasing it online.

After the hackers invoked the 9/11 attacks in their threats, the White House branded it a national security threat, and an investigation by the FBI said North Korea was behind the Sony intrusion.

Pyongyang repeatedly denied involvement, but has applauded the actions of the shadowy Guardians of Peace group.

Proportional response

The White House further stressed, on Friday, that its response will be “proportional”, but also that the sanction actions were only “the first aspect of our response”.

“We take seriously North Korea's attack that aimed to create destructive financial effects on a US company and to threaten artists and other individuals with the goal of restricting their right to free expression,” said White House press secretary Josh Earnest.

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In parallel with the White House announcement, the Treasury named the first targets of sanctions in the Sony case.

They included the Reconnaissance General Bureau, the government's main intelligence organisation, and two top North Korean arms exporters: Korea Mining Development Trading Corporation (KOMID) and Korea Tangun Trading Corporation.

The individuals named included agents of KOMID in Namibia, Russia, Iran and Syria, and other representatives of the government and the sanctioned organisations.

An administration official, briefing reporters, said that they remain “very confident” in their assessment that Pyongyang is behind the attack on Sony, amid doubts raised by security experts.

The official said the three organisations had “no direct involvement” with the hacking. “They're being designated to put pressure on the North Korean government,” the official said.

It was the first time the Treasury sanctions mechanism had been invoked due to a threat to a private company, the official acknowledged.

The sanctions forbid US individuals and companies from doing business with those blacklist, and freezes any assets those blacklisted might have on US territory.

A particular aim of such sanctions is to limit their access to international financial services by locking them out of the US financial system.

All three of the organisations blacklisted in the Sony case are already under US sanctions for the country's persistence with its nuclear weapons program, its alleged provocations on the Korean peninsula, and other “continued actions that threaten the United States and others”, as Obama said in his letter.