In some of the most unequivocal comments on the issue so far, the director of the National Security Agency (NSA) Michael Rogers this week labeled the leak of emails belonging to the Democratic National Committee in July as a deliberate action by a state actor with specific motives.

Rogers, who also heads the US Cyber Command, was responding to a question on the topic in an interview with the Wall Street Journal that was webcast this week.

“This was not something that was done casually,” Rogers said emphatically referring to the leak and the subsequent decision by whistleblower site WikiLeaks to publish the DNC emails.

“This was not something that was done by chance. This was not a target that was selected purely arbitrarily. This was a conscious effort by a nation state to attempt to achieve a specific effect.”

Rogers however stopped short of attributing the attack on any particular nation state. US officials and law enforcement have suggested evidence points to Russian involvement.  

A lone hacker using the name Guccifer 2.0, has so far been the only one to claim responsibility for the intrusion and theft of over 19,000 emails from the DNC server. Some security vendors have pinned the attack on Cozy Bear and Fancy Bear, two Russian advanced persistent threat groups that are believed to be working for the Russian government.

The leaked emails provided details on major donors of Hillary Clinton’s campaign while many others proved highly embarrassing to the party, prompting the resignation of DNC chair Debbie Schultz and several others.

Many have said the leaks were politically motivated with a view to damaging the Clinton campaign in the crucial last few months leading to the presidential election.

In his interview with the Journal, Rogers described the attack as unacceptable and not something that the US will take lying down. “We are serious, we are prepared to use multiple tools and multiple capabilities that are with our tool kit,” to get nation state actors and other threat groups to change such behavior, he said.

But any response the US takes will be measured and will likely vary depending on threat actor and malicious behavior he said.

Following the massive intrusion at Sony in 2014, for instance, the US came out publicly and formally identified North Korea as the culprit. It imposed economic sanctions against individuals, entities and a portion of the government in that country, Rogers noted. “We highlighted very publicly that this is a first step [and] that we are prepared to take additional action at a time and place of our choosing,” he said.

That response seems to have been effective because there has been no further attacks of the same scale from North Korea.

The U.S. approach with other countries has been different, Rogers said. For instance, in response to concerns about growing Chinese cyber espionage activities, the Obama Administration met with Chinese counterparts in Sept. 2015 and the two sides agreed not to use cyber tools for economic advantage.

“We certainly acknowledge that nation states will use cyber as a tool to generate insight and knowledge about what’s going on in the world around them,” he said. But it is unacceptable, he added, to take knowledge gained from legitimate intelligence-gathering purposes and provide it to the private sector for economic purposes, as some countries do.

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