First Read is your briefing from Meet the Press and the NBC Political Unit on the day's most important political stories and why they matter.

WASHINGTON — The most significant news Monday in Special Counsel Robert Mueller’s Russia probe wasn’t the indictments of Paul Manafort and Rick Gates — though it’s not every day that two high-ranking members of a president’s campaign team get indicted. Instead, the big news was from the guilty plea of a lower-ranking foreign adviser, George Papadopoulos.

Why? Because Papadopoulos’ plea (of lying to the FBI) contains what is now the SECOND known instance of Russians, using intermediaries, telling Trump officials that they have dirt on Hillary Clinton.

On or about April 26, 2016, defendant PAPADOPOULOS met [an overseas] 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."

That April 26 meeting came one month AFTER former Clinton Campaign Chair John Podesta’s emails were hacked.

The FIRST known instance of Russians, via intermediaries, telling Trump World they had dirt on Hillary Clinton was that June 3, 2016 Rob Goldstone email to Donald Trump Jr., which set up that meeting with a Kremlin-connected lawyer six days later:

Emin [Agalarov] just called and asked me to contact you with something very interesting.The Crown prosecutor of Russia met with his father Aras this morning and in their meeting offered to provide the Trump campaign with some official documents and information that would incriminate Hillary and her dealings with Russia and would be very useful to your father.This is obviously very high level and sensitive information but is part of Russia and its government's support for Mr. Trump — helped along by Aras and Emin.What do you think is the best way to handle this information and would you be able to speak to Emin about it directly?I can also send this info to your father via Rhona, but it is ultra sensitive so wanted to send to you first.

Donald Trump Jr. replied to that email, “If it’s what you say, I love it.”

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Those two known examples of people offering Team Trump knowledge of Russian dirt on Hillary Clinton come as President Trump has denied any “collusion” with Russia, calling the investigation “phony” and a “witch hunt.”

Mueller starts squeezing witnesses

The other significant angle regarding Papadopoulos is that he’s cooperating with the Mueller probe. Bloomberg News: “Jeffrey Cramer, a former federal prosecutor who’s now managing director of consulting firm Berkeley Research Group LLC, said that after Papadopoulos’s arrest in July, Mueller may have used him to make recordings that could result in charges against others. ‘Anyone who’s had a conversation with that guy since July until last night should be thinking about what they said to him,’ Cramer said.”

And according to prosecutors, Papadopoulos corresponded with a high-ranking Trump official — whom NBC News has identified as Manafort — about his conversations with Russians and their intermediaries.

(“The government notes that the official forwarded defendant PAPADOPOULOS's email to another Campaign official (without including defendant PAPADOPOULOS) and stated: "Let[']s discuss. We need someone to communicate that DT is not doing these trips. It should be someone low level in the campaign so as not to send any signal.")

A “campaign supervisor” commented to Papadopoulos about his Russian contacts/conversations: “Great work.”

Bottom line: Yesterday’s news was about witness squeezing — either through the indictments against Manafort and Gates, or letting Trump World know that they’ve flipped Papadopoulos.

Mueller is sending the message that he hasn’t received a lot of cooperation in his probe, and that he’s going to get that cooperation — one way or another.

Wanna get away?

It’s not ideal for President Trump that he’s embarking on his big Asia trip later this week with the Russia/Mueller cloud over his head. Then again, maybe it’s not a bad idea to get far away from Washington.

The Washington Post: “The president digested the news of the first indictments in special counsel Robert S. Mueller III’s probe with exasperation and disgust, these people said. He called his lawyers repeatedly. He listened intently to cable news commentary. And, with rising irritation, he watched live footage of his onetime campaign adviser and confidant, Paul Manafort, turning himself in to the FBI.”

“Initially, Trump felt vindicated. Though frustrated that the media were linking him to the indictment and tarnishing his presidency, he cheered that the ­charges against Manafort and his deputy, Rick Gates, were focused primarily on activities that began before his campaign. Trump tweeted at 10:28 a.m., ‘there is NO COLLUSION!’”

“But the president’s celebration was short-lived. A few minutes later, court documents were unsealed showing that George Papadopoulos, an unpaid foreign policy adviser on Trump’s campaign, pleaded guilty to making a false statement to the FBI about his efforts to broker a relationship between Trump and Russian President Vladimir Putin. The case provides the clearest evidence yet of links between Trump’s campaign and Russian officials.”

A week out from the New Jersey and Virginia gubernatorial contests

We’re now a week out from Election Day 2017.

Worth noting: The Latino Victory Fund TV ad that’s getting attention for its portrayal of a truck with a Confederate flag and an Ed Gillespie bumper sticker terrorizing children of color has only a small amount of money behind it.

The organization has booked $14,000 on cable from Nov. 1-6 on CNN and MSNBC, as well as another $14,000 for on a local Telemundo affiliate. (For reference: The cable buy only translates into about three airings total.)