(CNN) Former acting Attorney General Matthew Whitaker warned Russia is "trying to interfere in 2020" during remarks at the Oxford Union in the UK on Friday, remarks that came after it was revealed that a Capitol Hill briefing on Russia's continued election interference had angered President Donald Trump.

CNN has obtained a recording of Whitaker's remarks. Whitaker, who replaced Attorney General Jeff Sessions, told the audience at Oxford that law enforcement officials at the Justice Department and the FBI were constantly on guard against the Russian threat to US elections.

Then-acting US Attorney General Matthew Whitaker is seen in February 2019 testifying before Congress in Washington, DC.

"I am never going to deny that Russia tried to interfere in 2016," Whitaker said. "They tried to interfere in 2018. And they're trying to interfere in 2020," Whitaker said, adding the Kremlin's efforts go back to the Reagan administration.

"We have to be on guard," Whitaker said. "At the Department of Justice, especially at the FBI, we had a unique view as to how to interrupt their effort. It's a counterespionage, counterintelligence, all of the kind of things that you do when other countries are trying to interfere in your domestic elections."

The intelligence community's top election security official delivered a briefing to lawmakers last week warning them that the intelligence community believes Russia is already taking steps to interfere in the 2020 election with the goal of helping Trump win, three sources familiar with the matter tell CNN. Last week's briefing, led by election security official Shelby Pierson and first reported by The New York Times , addressed the overall picture of Russia's efforts, including hacking, weaponizing social media and attacks on election infrastructure, one of the sources said.

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