How after 9/11, all the cats in America became sad?

Tears were just rolling down their faces. You'd see one sitting under a tree, tilting its head in that way they have, and then you'd notice its lower lip trembling. We've got two cats at our house, and one of those fake birds on a string, but back then, when you'd whip that bird across the floor, right under their noses, they'd just look at you...