President Donald Trump on Saturday announced that federal authorities had made “multiple arrests” of people he said were vandalizing the Reflecting Pool as he struggled to explain why the $14-million-plus rehabilitation project he launched for the nation’s 250th anniversary seemingly backfired.

Trump said his predecessors had let the pool turn an algae-stained green and that he’d line it with “American flag blue” so it better reflected the Washington Monument. But after the new pool was unveiled, its blue tinge quickly became a familiar green. Workers treated it with chemicals to kill the algae, but then the painted blue lining on the bottom began to peel.

On Friday night, Trump posted about the pool.

“We’ve had some real problems with Vandalism at the beautiful Reflecting Pool,” he posted on his social media site Friday night. “Just like three days ago, they destroyed the grass outside of the Pool, they’ve also done everything possible to hurt the inside surface that was just installed.”

He offered no details to substantiate his claim.