Remember recent reports that the special counsel's office was looking into the influx of pro-Russian Ukrainians who flooded into Donald Trump's inaugural events? The Ukrainian attendees were particularly interested in facilitating a supposed Ukrainian "peace plan" that would de-escalate tensions between the U.S. and Russia over the Kremlin's 2014 annexation of Crimea.

That peace deal, which focused in part on lifting sanctions the U.S. had imposed on Russia, appears to be a central part of the special counsel's inquiry into potential collusion between the Trump campaign and Russia. The new insight stems from a heavily redacted transcript from a closed-door session in a Washington courtroom last week regarding the case of former Trump campaign chair Paul Manafort. As a federal prosecutor argued that Manafort had violated his plea agreement, he may have unwittingly cracked open the door ever so slightly on what's driving the conspiracy portion of special counsel Robert Mueller's investigation.

According to Mueller's team, Manafort lied to them repeatedly about both his continued contacts with Russia ally Konstantin Kilimnik and the nature of those discussions. The communications allegedly began in early August 2016 and ran all the way through to 2018, even after Manafort's initial indictment. Mueller's team believes the Ukrainian peace deal was central to their discussions, which means they would have been hatching the pro-Russian plan just as Russia stepped up its efforts to augment Trump's campaign in the general election. The special counsel has tied Kilimnik to Russian intelligence.

In an exchange highlighted by the New York Times, the federal judge pressed prosecutor Andrew Weissmann about how Manafort's continued lies regarding his communication with Kilimnik mattered materially to the case they were building.

“This goes to the larger view of what we think is going on, and what we think is the motive here,” Mr. Weissmann said. “This goes, I think, very much to the heart of what the special counsel’s office is investigating.”