As Election Day approached in 2016, Russian President Vladimir Putin knew a lot of things about the Republican candidate for president that American voters didn't. He knew, for example, that Donald Trump had been hoping to build a skyscraper in Moscow and that Trump's attorney had even spoken with one of Putin's team about it. He knew, too, that Trump had downplayed his efforts to do business in Russia.
He knew that members of Trump's team had been trying to set up a meeting between the candidate and Putin. He knew that a lawyer linked to his team had actually met with Trump campaign staffers at Trump Tower.
He knew that Russia had interfered in the election, had stolen emails and disseminated posts on social media to disrupt the political conversation and submarine Hillary Clinton. Every time Trump praised WikiLeaks, Putin knew that Trump was praising Russia's efforts, even if Trump didn't.
Putin also knew that Americans didn't know these things. That, potentially, gave him leverage -- just as other secret information Putin might now hold could give Russia leverage.
Toward the end of former special counsel Robert Mueller's Capitol Hill testimony on Wednesday, Democratic representatives sitting on the House Intelligence Committee began to press Mueller on this point.
Rep. Raja Krishnamoorthi, D-Ill., noted that counterintelligence investigations -- that is, investigations into ways in which foreign intelligence agencies might seek to compromise government officials -- were outside of the scope of the special counsel's probe.
"Since it was outside your purview, your report did not reach counterintelligence conclusions regarding any Trump administration officials who might potentially be vulnerable to compromise or blackmail by Russia, correct?" Krishnamoorthi asked.
Mueller confirmed that this was correct, noting that those investigations would be housed at the FBI.
Krishnamoorthi quickly walked through often-murky links between Russian actors and Trump's private business, links like the Moscow skyscraper deal or past purchases of Trump properties by Russians. (Mueller declined to indicate if his team had obtained Trump's tax returns.) Krishnamoorthi then turned to the broader point.
"Individuals can be subject to blackmail if they lie about their interactions with foreign countries, correct?" he asked.
"True," Mueller replied.
While former national security adviser Michael Flynn did plead guilty to lying to Mueller's team, Krishnamoorthi said, "your report did not address how Flynn's false statements could pose a national security risk because the Russians knew the falsity of those statements, right?"
"I cannot get into that," Mueller replied, "mainly because there are many elements of the FBI that are looking at different aspects of that issue."
"Currently?" Krishnamoorthi asked.
"Currently," Mueller replied.
"Different aspects of that issue" is vague and presumably refers to questions about Flynn specifically. That said, though, Flynn's case has largely been resolved and he will soon be sentenced for the false statements he made to Mueller's team. The extent to which Flynn is the subject of a current counterintelligence investigation is unclear - and so, therefore, is the scope of that "different aspects" comment.
In May, House Intelligence Committee chairman Adam Schiff, D-Calif., spoke with The Washington Post about how the counterintelligence investigation into Trump himself had gone dark since former FBI director James B. Comey was fired.
"This all began as an FBI counterintelligence investigation into whether people around then-candidate Trump were acting as witting or unwitting agents of a foreign power," Schiff said then. "... We would get briefed, predominantly at a Gang of Eight level, up until Comey was fired. And, after that point, while we continued to get quarterly -- although often they missed the quarterly nature of it -- counterintelligence briefings, they excluded the most important counterintelligence investigation then going on, that involving Donald Trump."
He referred to the discrepancy between what Putin knew and what was public as "quintessential counterintelligence issues" and expressed concern that the investigation might have been shut down.
Schiff raised this same question to Mueller on Wednesday. He noted that January 2016 conversation between President Trump's former attorney Michael Cohen and a staffer in Putin's spokesman's office.
"If candidate Trump was saying, I have no dealings with the Russians, but the Russians had a tape recording [of the Cohen conversation], they could expose that, could they not?" Schiff asked.
"Yes," Mueller replied.
"That's the stuff of counterintelligence nightmares, is it not?" Schiff said.
"It has to do with counterintelligence and the need for a strong counterintelligence entity," Mueller replied.
Schiff then stated that Trump's response to the Trump Tower Moscow deal being made public was twofold. The first was to say that the discussions weren't a crime. The second was that he was lining things up in case he lost.
"There was a good chance that I wouldn't have won," Trump said last November, "in which case I would have gone back into the business, and why should I lose lots of opportunities?"
"Were you able to ascertain -- because he wouldn't answer your questions completely -- whether or if he ever ended that desire to build that tower?" Schiff asked Mueller.
"I'm not going to speculate on that," Mueller replied.
"If the president was concerned that if he lost his election, he didn't want to miss out on that money," Schiff continued, "might he have the same concern about losing his reelection and missing out on that money?"
"Again, that's speculation," Mueller said.
"The difficulty with this, of course, is we are all left to wonder whether the president is representing us or his financial interests," Schiff said.
And with that, Mueller's time on the Hill was over.