Donald Trump Jr. used Instagram Tuesday night to endorse his father's border wall policy, saying the evidence that a wall works is because they protect people from zoo animals.

"You know why you can enjoy a day at the zoo? Because walls work," Trump Jr., 41, wrote in his Instagram story.

President Trump has proposed erecting concrete walls and steel slats to keep undocumented immigrants out of the U.S. Trump Jr.'s post came shortly after the president's Tuesday night Oval Office address, in which he declared a "crisis" at the southern border. Democrats said he had "chosen fear."

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Trump Jr. has made controversial analogies on social media before, like when he compared Syrian refugees to a bowl of Skittles, in which some of the candies are poisoned.