Donald Trump’s former campaign chairman, Paul Manafort, pleaded guilty to two counts in his new Washington criminal case, and admitted guilt in the 10 counts outstanding from his earlier trial in federal court in Virginia. The shocking part is this: He agreed last week to cooperate with federal prosecutors. A more accurate statement would be that federal prosecutors have agreed to “cooperate” him. As with most cooperation agreements, Manafort will have to “come clean” and be completely forthcoming with documents and information, and voluntarily testify in court.

If Manafort gives the government substantial assistance, the sentencing benefits are significant. The government will file a motion for a “downward departure” from the sentencing guidelines for cooperation, and for an additional reduction (up to three “levels”) for “acceptance of responsibility.” These alone can reduce the sentence by decades.

Many are suggesting Trump should be worried about this situation, because Manafort very likely could have impressed special counsel Robert Mueller with what he knows about Trump. It’s also been suggested that Manafort has ended up in the worst situation by waiting so long to cooperate.

That line of thinking goes like this: Manafort is facing stiff prison sentences in two courts after having spent a fortune preparing for and going to trial. But now, he also has to “flip” and testify against Trump, foreclosing the possibility of a pardon, and making his investment in two trials for naught.

Consider another scenario, however: What if this agreement is for cooperation against a high-level government official, but it’s not Trump? What if it’s not even an American official?

Mueller’s original mission was to investigate Russian collusion with the Trump campaign. To date, he’s indicted a lot more Russians than he has Americans — even though the Americans are the ones being convicted. No less than 25 Russians have been indicted, though most may never be brought to the United States for prosecution.

Mueller might want to indict the high-level officials, or even the president … of Russia. Or at least name them as unindicted co-conspirators.

If anyone knows Russians, or Ukrainians, or Eastern Europeans in general, it’s Manafort.

This theory fits Trump’s longstanding positive position on Manafort, as compared to the president’s former attorney and cooperator Michael Cohen. When Cohen flipped and implicated Trump in crimes, Trump immediately began blasting Cohen on Twitter. By contrast, Trump has praised Manafort throughout his prosecution and trial. Trump also did not immediately disparage Manafort after he cooperated.

The president’s first tweet on Saturday instead attacked Mueller, calling his investigation the “Rigged Russian Witch Hunt.” Also on Saturday, Trump attorney Rudy Giuliani tweeted that Manafort’s cooperation agreement “does not involve the Trump campaign,” reiterating again that there was “no collusion with Russia.”

Trump doesn’t appear as concerned about Manafort’s cooperation as he has been about other cooperators or aspects of the investigation. It’s still possible Manafort has damaging information about Donald Trump Jr., or Jared Kushner, and the president doesn’t know this, or is unwilling to believe it. The only thing he appears confident about so far is that Manafort can’t hurt him.

For this to be true, several other things must be true: First, Manafort must have had information reliable and valuable enough to merit a cooperation agreement from prosecutors. Second, that information was about a “bigger fish” than Manafort. Third, if the bigger fish isn’t Trump, it still has to be big, even if it's in a country other than the United States.

In this way, Manafort could simultaneously be the most significant cooperator in the Russia probe, but also perceived by Trump to not be a serious threat to him.

Meanwhile, the most dangerous cooperator to date is still unquestionably Michael Cohen, who explicitly implicated the president in open court when he pleaded guilty and gave a factual basis on the record for campaign finance crimes.

Manafort has something of value for Mueller. It’s possible it’s not the president — of the United States.

Danny Cevallos is an MSNBC legal analyst. Follow @CevallosLaw on Twitter.