After former Acting Attorney General Sally Yates and former Director of National Intelligence James Clapper testified on Capitol Hill Monday, President Trump took to Twitter to dismiss their revelations.

Trump tweeted that there is "no evidence" of collusion between himself and Russia, that Yates didn't reveal anything new during her testimony, that the investigation into collusion between Russia and Trump is a "total hoax," and that the media should be reporting on surveillance instead, finishing off the string of tweets with the hashtag, "#FakeNews!"

VIDEO: Sally Yates details warning Trump about Michael Flynn

But here are four reasons why the entire Russia story — as it relates to the 2016 election, to former Trump National Security Adviser Michael Flynn, and to any allegations of collusion — isn't fake news.

1. Russia interfered in the 2016 election and could do so again: "If there has ever been a clarion call for vigilance and action against a threat to the very foundations of our democratic political system, this episode is it. I hope that the American people recognize the severity of this threat and that we collectively counter it before it further erodes the fabric of our democracy," Clapper said yesterday.

2. The FBI is investigating whether the Trump campaign coordinated with Russia: "I have been authorized by the Department of Justice to confirm that the FBI, as part of our counterintelligence mission, is investigating the Russian government's efforts to interfere in the 2016 presidential election," FBI Director James Comey said back in March. "And that includes investigating the nature of any links between individuals associated with the Trump campaign and the Russian government — and whether there was any coordination between the campaign and Russia's efforts.

3. There appears to be an investigation into Trump's business ties to Russia: When Sen. Lindsey Graham (R-SC) asked Clapper yesterday if he ever found a situation where a Trump business interest in Russia gave him concern, Clapper replied, "Not in the course of the preparation of [last winter's] intelligence community assessment." When Graham pressed if he later found a concern, Clapper said, "Sen. Graham, I can't comment on that because that impacts the investigation."

4. It took 18 days for the Trump White House to oust Flynn after being notified by the Justice Department that Flynn wasn't telling the truth about his conversations with Russia's ambassador: "Yates said [White House Counsel Don] McGahn asked her, 'Why does it matter to the DOJ if one White House official lies to another official?' She explained that the American public was being misled, and that the Russians knew that. 'To state the obvious, you don't want your national security adviser compromised by the Russians,' Yates said she replied," per NBC's Ken Dilanian.