Bob Woodward joined Bill O'Reilly tonight to react to the resignation of National Security Adviser Michael Flynn and allegations about any possible Trump administration ties to Russia.

Flynn stepped down in the wake of revelations surrounding conversations he had with the Russian ambassador last year and several reports that he was not honest with Vice President Mike Pence about the situation.

Woodward, who gained fame investigating the Watergate scandal, said he doesn't buy the explanation that Flynn was pushed out because he misled Pence.

"All my alarm bells went off. Why is he gone for this?" Woodward wondered. "I think lots of people had the same feeling who are in the media. So they're asking the question, 'What really goes on here?'"

O'Reilly argued that misleading the vice president is indeed a fireable offense, and there's no evidence to justify asking speculative questions.

"If I were you, I'd sue anybody saying this is Watergate," O'Reilly quipped.

Woodward insisted that the White House counsel should investigate and put out a full report of exactly what really happened, in order to answer lingering questions.

"Believe me, this is going to fester for weeks, if not months, if there aren't answers to very serious questions," he said.

Watch more above, and let us know what you think in the comments.

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