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Former White House national security adviser Michael Flynn pleaded guilty Friday to lying to the FBI about contacting Russian officials on behalf of then-President-elect Donald Trump.

The plea by Flynn, the first White House official to be charged in special counsel Robert Mueller's investigation, electrified Washington and set off intense debate among legal minds about what it portended for the future of the Trump White House.

Andrew McCarthy, a former Assistant U.S. Attorney, argued that Flynn's admission may not be a significant break in Mueller's investigation.

"[Flynn], like [former Trump campaign adviser George] Papadopoulos ... is being permitted to plead guilty to a mere process crime," McCarthy wrote on National Review Online. "[F]or for all the furor, we have a small-potatoes plea in Flynn’s case ... despite extensive 'collusion' evidence."

McCarthy went on to argue that "[i]t is becoming increasingly palpable that, whatever 'collusion' means, there was no actionable, conspiratorial complicity by the Trump campaign in the Kremlin’s machinations." McCarthy also noted that Mueller's other significant criminal case, against Trump's former campaign chairman Paul Manafort, "has nothing to do with the 2016 election."

However, Los Angeles defense attorney Ken White, himself a former assistant U.S. attorney, posted on Twitter that he was not as confident as McCarthy in the absence of a wider conspiracy.

"You generally spell out the entire conspiracy in a cooperator's guilty plea -- in many cases," White wrote. "With more sophisticated cooperators ... you play the cards closer to the vest.

"Yes, you'd get a drug mule to spill to the whole conspiracy in the plea to lock them in," White added. "A Flynn? Maybe not."

National security lawyer Steve Vladeck echoed White, tweeting that "the story isn't that Michael Flynn is pleading guilty. It's what he's giving Mueller in exchange for such a minor charge ..."

"We may not know the answer to that for some time," Vladeck added, "but I have to think it's substantial."

Fox News judicial analyst Andrew Napolitano was less circumspect, characterizing Flynn's plea as "a nightmare for Donald Trump" and "probably the tip of a prosecutorial iceberg."

However, Napolitano also told "Shepard Smith Reporting" that if Trump told Flynn to reach out to Russian officials after his election last year, that may not be an impeachable offense, though "they certainly are in the category of offenses that are impeachable."

"Beyond this, the president of the United States has steadfastly, repeatedly and consistently denied that he had any knowledge of any involvement with the Russians," Napolitano added. "If Gen. Flynn contradicts that in a credible way under oath, we have a very serious problem on our hands."