The apparent coziness between the Trump administration and the Russian government could be the nation’s biggest scandal since Watergate, legendary TV journalist Dan Rather warned Tuesday.

“Watergate is the biggest political scandal of my lifetime, until maybe now,” Rather wrote in a Facebook message that quickly went viral.

“On a 10 scale of armageddon for our form of government, I would put Watergate at a 9,” added Rather, who won acclaim for his coverage of Watergate as a White House correspondent. “This Russia scandal is currently somewhere around a 5 or 6, in my opinion, but it is cascading in intensity seemingly by the hour.”

Rather’s analysis was a response to the resignation of President Donald Trump’s national security adviser, Mike Flynn, late Monday and the questions it has raised about the Trump administration’s ties to Russia.

Flynn resigned after a series of reports revealed he had not been honest when he denied discussing sanctions on a December phone call with the Russian ambassador to the United States. The Washington Post on Monday, in an article that prompted his resignation, reported that then-acting Attorney General Sally Yates had informed the White House weeks ago that Flynn had not been honest to senior administration officials about his conversation with the Russian ambassador and may have made himself vulnerable to extortion by the Russian government.

The disclosures provide fodder for Trump critics like Rather, who are concerned that the new administration is too chummy with the Russian government to properly advocate for American interests. U.S. intelligence agencies believe that Russia ordered the hacking of Democratic campaign emails with the goal of electing Trump last year. As president, Trump has refused to criticize Russian President Vladimir Putin and indicated that he would like to mend relations with the country.

On Tuesday, Rather was one of many journalists asking how long Trump had known about Flynn’s deception and why he did not act sooner.

“We are still less than a month into the Trump Presidency, and many are asking that question made famous by Tennessee Senator Howard Baker those many years ago: ‘What did the President know, and when did he know it?’” Rather wrote, quoting Baker’s question about President Richard Nixon during the Senate’s investigation of the 1972 break-in at Democratic National Committee headquarters in the Watergate building.

Keith Bedford / Reuters Broadcast journalist Dan Rather has developed a new following on Facebook thanks to his writings about the Trump presidency.

Trump did not discipline Flynn sooner because he wanted to give the retired lieutenant general “due process” and the White House counsel maintained that Flynn had not violated the law, White House Press Secretary Sean Spicer said Tuesday. Trump ultimately demanded Flynn’s resignation over Flynn’s denial to Vice President Mike Pence that he had discussed sanctions on the call, which led Pence to repeat the lie on television, according to Spicer.

Rather called for an independent investigation of the matter, arguing that the administration and the Republican Congress have forfeited their right to be trusted on these matters.

“Damn the lies, full throttle forward on the truth,” he concluded.

Rather, best known for serving as host of “CBS Evening News” from 1981 to 2005, has developed a large and devoted Facebook following for his ominous screeds about the dangers of the Trump presidency. Rather also hosts an interview show on cable channel AXS TV.