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U.S. officials are confident that defensive measures put in place will stop Russia from hacking more emails to influence the upcoming election — for now.

A high-level intelligence source said the U.S. and its allies have choked off cyber paths that the Russians have allegedly been using to steal emails from high-profile Democrats and other prominent Americans and make them public through WikiLeaks, DCleaks and Guccifer 2.0.

The Russians, both the state actors and their proxies, are some of the most sophisticated cyber actors in the world and so it won't take them long to find ways of infiltrating and attacking new systems getting access to more data and certainly trying to use it for information, warfare or other purposes.

"I think it's credible that the U.S. government is doing everything possible to stop the cyber bleeding," said Juan Zarate, who was a top counterterrorism official from 2005 to 2009.

But, he added, it's all but certain that the Russians will eventually find work-arounds.

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"The Russians — both the state actors and their proxies — are some of the most sophisticated cyber actors in the world and so it won't take them long to find ways of infiltrating and attacking new systems, getting access to more data and certainly trying to use it for information, warfare or other purposes.

"This isn't going to be the end of the story by any stretch."

Related: U.S. Publicly Blames Russian Government for Hacking

Wikileaks has put out tens of thousands of emails, including batches from the Democratic National Committee and from Hillary Clinton's campaign chair John Podesta, which contained transcripts of her paid speeches to Goldman Sachs.

Although Wikileaks was posting as recently as this week, none of the material is from after March 2016. The latest known theft is Colin Powell's emails, many of which were from August and were disseminated by DCleaks.

The hackers and leak sites are believed to have emails they have not yet made public, but the U.S. is confident that its countermeasures mean the Russians cannot steal more right now.

Washington is not just playing defense.

Related: CIA Prepping for Possible Cyber Strike Against Russia

As NBC reported last week, the Obama administration is contemplating an unprecedented cyber covert action against Russia in retaliation for alleged Russian interference election, according to U.S. intelligence officials.

Current and former officials with direct knowledge of the situation told NBC News that the CIA has been asked to deliver options to the White House for a wide-ranging "clandestine" cyber operation designed to harass and "embarrass" the Kremlin leadership.

No action can be taken without a presidential order and the administration is divided over what to do.

Russia has denied it's behind the hacking and last week President Vladimir Putin declared, "We have no intention of influencing the election campaign in the U.S."