On Friday morning, Donald Trump’s former campaign chairman Paul Manafort pled guilty in federal court in Washington, D.C. to two counts of conspiracy relating to his work as an unregistered agent for pro-Russian Ukrainian politicians, among other crimes. Manafort pled guilty not to a straight plea agreement — where both sides give a little, cut their losses, and go their separate ways — but, stunningly, to a cooperation agreement. Paul Manafort’s cooperation agreement with special counsel Robert Mueller is an existential threat to the Trump presidency.

During Friday’s plea proceeding, Mueller’s deputy Andrew Weissman stated on the record that Manafort already has proffered with Mueller’s team. That means that, at a minimum, the process of downloading information from Manafort has begun, and presumably has gotten far enough along that Mueller felt comfortable making a deal with Manafort.

Of course, now that he has pled guilty and agreed to be sentenced for all of his criminal conduct, Manafort now has to actually cooperate with Mueller. That means, in essence, that Mueller now owns Manafort. Manafort has to do everything Mueller asks: provide information to investigators upon request, testify in the grand jury, turn over documents to Mueller, and testify at trial. If Manafort is truly on board as a cooperator, then Mueller knows, or soon will know, everything Manafort knows. That must be a scary thought for the president.