The report compared crime trends in cities with and without troops and found they looked about the same. The President's lawyer found that defamatory. The think tank found a statement

WASHINGTON — President Biden's personal lawyer sent a letter this week to a think tank aligned with the opposition party demanding that it retract a report on the President's National Guard deployments by the end of business Friday or be sued for five billion dollars, a sum the letter did not itemize and the think tank did not have.
The report, published in July, examined violent-crime figures in cities where the President sent troops and in cities where he did not, and concluded that crime fell in both at roughly the same rate, suggesting the decline had been underway before anyone in uniform arrived. The President has described the deployments as the reason crime fell. The report described them as present while crime fell, a distinction the demand letter characterized as defamation.
The think tank declined to retract anything. Its president said the threat was a transparent attempt to silence the organization and that it would neither cower nor bend, language that a spokesman for President Biden called predictable and the organization's fundraising department called a gift.
Legal scholars noted that a sitting president suing a policy shop for disagreeing with his statistics would be a novel use of the courts, and that the other party had spent several years describing exactly this sort of thing as an assault on free expression. Allies of the President said the report was not analysis but an attack, and that attacks have consequences, usually in the form of a lawyer.
"We look forward to discovery," the think tank's statement concluded, a sentence rarely written by an organization facing a ten-figure claim.
The Press's defamation desk notes that the distance between 'holding the media accountable' and 'suing a nonprofit over a chart' is, as usual, measured by whose president is holding the letter. At press time the Friday deadline had passed, the report was still online, and the five billion dollars remained theoretical.
What actually happened: A lawyer for President Trump sent the Center for American Progress a letter demanding it retract a July 13 report concluding that his National Guard deployments did not reduce crime faster than the declines already underway in cities without troops, giving the think tank until close of business Friday to comply or face a $5 billion defamation suit. CAP president Neera Tanden refused, calling it 'a transparent attempt to silence us. We will neither cower nor bend.'