President Donald Trump on Thursday said he won’t sack Washington’s top federal prosecutor over her decision to drop unsubstantiated charges against a former Olympic paddler last week but continued to insist that the Lincoln Memorial Reflecting Pool had been vandalized despite no evidence to support his allegations.

Trump told NBC News in a phone interview that Pirro, a former New York prosecutor and judge who spent years as one of his most fervent defenders on Fox News, had “made a big mistake” in asking the District of Columbia Superior Court to dismiss charges against David Hearn, the ex-Olympian who’d been facing ten years in prison for touching part of the reflecting pool liner that had detached from the bottom of the pool.,

“She said there was no vandalism. There was tremendous vandalism,” he said. “So, she made a terrible mistake. I don’t understand why she did such a stupid thing.”

But when pressed on whether she’d be fired for the decision, Trump replied: “I think she made a terrible decision. That doesn’t mean change.”

The president continued to insist the century-old water feature had been vandalized despite Pirro’s assertion in court documents that the damage to the liner that had been applied by his handpicked contractor “was the result of a botched installation and not vandalism.”

Her motion before the court blamed “contractor error” and added that it would be “ difficult to attribute the widespread damage to the Reflecting Pool to vandalism, let alone to establish that fact beyond a reasonable doubt.”

Pirro had previously lambasted Hearn in a press conference on July 2, claiming he “woefully destroyed property” in a “deliberate act” to damage the monument by “forcefully and violently” pulling the pool’s lining.

But the longtime prosecutor accused the Department of the Interior of providing her office with “less than fulsome information” about the case, leading to a confrontation in the Oval Office last week.

The shallow pool, which the president repeatedly promotes as “bigger than skyscrapers,” was refurbished with a shade of dark blue and outfitted with “advanced nanobubbler technology” to tackle algae blooms that have long plagued the landmark.

Algae returned shortly after the renovations were complete, and the new sealant started to peel off in chunks that bubbled to the surface.

Trump initially said a refurbishing project for the 2,030-foot pool could be done quickly for $1.5 million in time for White House-backed Fourth of July celebrations.

His administration has now spent nearly $14.7 million, with all funds directed to Atlantic Industrial Coatings LLC, Virginia, according to federal spending records.

Hearn’s attorneys have asked the case against him to be dismissed with prejudice to deny the government any chance of refiling them, citing Trump’s repeated assertions that the pool was damaged by vandalism even after Pirro’s court filing exonerated him.

Alex Woodward contributed reporting from New York