This paragraph from the FBI's guilty plea agreement with Papadopoulos is incredible:

"In truth and in fact, however, and as set forth above, defendant PAPADOPOULOS met the Professor for the first time on or about March 14, 2016, after defendant PAPADOPOULOS had already learned he would be a foreign policy advisor for the Campaign; the Professor showed interest in defendant PAPADOPOULOS only after learning of his role on the Campaign; and the Professor told defendant PAPADOPOULOS about the Russians possessing" dirt" on then-candidate Clinton in late April 2016, more than a month after defendant PAPADOPOULOS had joined the Campaign."

So, Papadopoulos copped to lying to the FBI about the timing of his contacts with Russians. In his initial interview in January 2016, Papadopoulos was insistent that he had reached out to his foreign contact "The Professor" (amazing!) before he had formally joined the Trump presidential campaign. He was arrested in July, pleaded guilty in October and appears to have been cooperating in between.

And, most importantly the "Professor" only showed interest in Papadopoulos after it became known that he was employed by the Trump campaign.

That. Is. A. Very. Big. Deal.

The obvious question is why Papadopolous initially lied to the FBI -- despite being warned that doing so would have major consequences. Why, if there was nothing to hide about his relationship -- or attempted relationship with Russian officials -- would Papadopoulos feel the need to put himself in serious legal jeopardy by lying about the timing of his conversations with "the Professor"?

We don't know the answer to that question. But, we do know one reason why Papadopoulos was pursuing the relationship with the Russians; he believed they had "dirt" on Hillary Clinton. This, again from Papadopoulos' plea agreement, makes that plain:

"On or about April 26, 2016, defendant PAPADOPOULOS met the Professor for breakfast at a London hotel. During this meeting, the Professor told defendant PAPADOPOULOS that he had just returned from a trip to Moscow where he had met with high-level Russian government officials. The Professor told defendant PAPADOPOULOS that on that trip he (the Professor) learned that the Russians had obtained "dirt" on then-candidate Clinton. The Professor told defendant PAPADOPOULOS, as defendant PAPADOPOULOS later described to the FBI, that "They [the Russians] have dirt on her"; "the Russians had emails of Clinton"; "they have thousands of emails."

The broad goal of the Russian contact with Papadopoulos was to get Trump to visit Russia during the campaign -- a visit where he would huddle with Russian officials and maybe even meet with Russian President Vladimir Putin.