President Donald Trump declares a national emergency at the U.S.-Mexico border while speaking about border security in the Rose Garden of the White House in Washington, February 15, 2019.

President Donald Trump on Monday suggested that key officials involved in the Russia probe were engaged in "treasonous" behavior.

Trump lashed out on Twitter at former FBI Deputy Director Andrew McCabe, whose new book details his concerns about potential foreign influence over the president, and current Deputy Attorney General Rod Rosenstein, who initiated special counsel Robert Mueller's investigation.

Trump said McCabe and Rosenstein "look like they were planning a very illegal act, and got caught."

In an interview with CBS's "60 Minutes," McCabe, who was fired last year by the FBI, described Rosenstein as having raised the prospect of invoking the 25th Amendment to remove Trump from office.

"This was the illegal and treasonous 'insurance policy' in full action!" he said in the tweet.

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The Justice Department and a spokeswoman for McCabe could not immediately be reached for comment.

— CNBC's Tyler Clifford contributed to this report