"There are known knowns," former Defense Secretary Donald Rumsfeld famously said in 2002. These are often called facts.

Sounds obvious enough, but Rumsfeld was actually making an important point about the nature of information and how we process it. He continued: "We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns -- the ones we don't know we don't know."

In the Kremlin-gate scandal, we -- meaning the public in general -- remain mostly in the realm of unknown unknowns. We're probably going to have to wait for the FBI's investigation to be completed -- or the emergence of a Deep Throat for a 21st century Woodward and Bernstein -- before we move into known knowns that allow us to determine whether Donald Trump's presidential campaign last year colluded with Russian spies and hackers to tilt the election.

But some people are further down the Rumsfeldian road than others. Conservative national-security specialists -- who tend to be Trump critics -- have been cultivating their sources in the U.S. intelligence community for months. And they are increasingly convinced that the Trump campaign did indeed collude with the Russians -- and that Trump himself knew about it and inevitably is going to face impeachment and maybe even worse.

Here's how a post from Louise Mensch's Patribotics blog opened on Sunday:

"Sources linked to the intelligence community say that General Mike Flynn's trips to Cambridge and across Europe will form a key part of Donald Trump's impeachment and the prosecutions of dozens of his associates. According to several sources within the intelligence community, Michael Flynn was coordinating, with and for Russian agents, the drafting of messages that Vladimir Putin was using to attack democracy in not only the United States, but across Europe. Furthermore, Flynn was doing this with the full knowledge of the Trump campaign, including Donald Trump himself."

Mensch, a former Conservative member of the British Parliament and the founder of Rupert Murdoch's Heat Street news site, has been called a right-wing conspiracy theorist, but she's been out front on -- and right about -- key aspects of Kremlin-gate going back to last fall. Flynn, of course, was President Trump's national-security adviser until he was forced to resign for lying about his contacts with the Russian ambassador to the U.S. It was revealed last month that he was seeking immunity from the FBI or Congress in exchange for his testimony.

Exclusive: Intelligence Sources: Flynn co-ordinated Russia's propaganda attack on the entire NATO alliance for Trump https://t.co/X0SgA9FJeh — Louise Mensch (@LouiseMensch) April 16, 2017

Much of the information that is fueling reports such as Mensch's apparently comes from communications intercepts -- the routine monitoring of foreign agents by the National Security Agency. It seems that various Trump campaign officials and advisers ended up on these intercepts talking with known foreign spies.

"Just got an EM fm [sic] senior IC friend, it began: 'He will die in jail,'" former NSA analyst John Schindler, now a conservative columnist, wrote on Twitter in February. The "he" Schindler's IC friend was referring to is President Trump.

And these intercepts aren't all coming from the NSA. Spy agencies from U.S. allies in Europe have shared their communications haul with the U.S. intelligence community and the FBI. "The key to unraveling the Trump Crime Syndicate are the foreign intercepts," former Bill Clinton administration White House staffer Claude Taylor recently wrote. "Real progress was made after Brits, Germans and other IC shared."

Taylor is convinced Flynn isn't the only big-name Trump campaign adviser who's going to end up dropping a dime on Trump. (And FBI Director James Comey probably will need their cooperation if he's hoping to go after the president, seeing as classified information -- such as from intelligence-service communications intercepts -- can't be used in court.)

Just spoke to a New York source and Rudy Giuliani is in legal jeopardy and is desperate to make a deal but James Comey is having none of it. — Claude Taylor (@TrueFactsStated) April 13, 2017

The question may not be has Carter Page flipped but when did he flip? Latest word is that FBI got to him early last summer and he was wired. — Claude Taylor (@TrueFactsStated) April 15, 2017

One of Kremlin-gate's many rabbit holes leads to Trump's possible financial ties to Russia, which allegedly go back long before the 2016 election campaign and involve the Russian mafia. To be sure, like everything else about the scandal so far, this subject is driven more by speculation than hard fact.

New York State Attorney General Eric Schneiderman "is expected to bring RICO indictments in the Trump-Russia scandal," the independent investigative-journalism site the Palmer Report wrote last week, citing two "reliable sources." The Racketeer Influenced and Corrupt Organizations Act is typically used to target organized crime.

Then there's former MI6 chief Sir Richard Dearlove, who says Trump was in Russia's debt even before Vladimir Putin's government started messing with the U.S.' democratic process. "What lingers for Trump may be what deals -- on what terms -- he did after the financial crisis of 2008 to borrow Russian money when others in the West apparently would not lend to him," he told Prospect magazine last week.

Dearlove, unlike many others who are predicting the worst for Trump, is not a participant in the American partisan battles. He's a retired British spy chief who's kept track of the growing threat from Putin's government through a "few well-placed Russians."

So the plot, as the saying goes, continues to thicken. And it's already so thick that it's difficult for us -- again, meaning the public in general -- to see clearly what has happened and is happening.

When, you are no doubt wondering, will all of this come to a head? That, alas, remains an unknown unknown.

I have a few good sources-Sadly, none work for Comey. https://t.co/mYx5JdOp5l — Claude Taylor (@TrueFactsStated) April 17, 2017

-- Douglas Perry