The president’s eldest son, Donald Trump Jr., said Tuesday that zoo enclosures show “walls work” as the partial government shutdown over funding for the president’s border wall continues.

“You know why you can enjoy a day at the zoo?” Trump asked in an Instagram story. “Because walls work.”

The comment drew condemnation on social media.

Trump’s Instagram post came on the same day the president argued that a wall along the U.S.-Mexico border is necessary to ensure national security.

“Some have suggested a barrier is immoral. Then why do wealthy politicians build walls, fences and gates around their homes?” the president asked Tuesday night. “They don’t build walls because they hate the people on the outside, but because they love the people on the inside.”

It’s not the first time the younger Trump has faced censure for his social media posts. He was criticized in 2016 after comparing Syrian refugees to poisoned Skittles candies.