Last week, a nine-year-old girl was walking to school with her brother and two friends in San Ysidro, San Diego, when she was stopped by immigration officials, according to reports. The girl was an American citizen; she even had a U.S. passport card with her. The officials detained her nonetheless—for around 32 hours, no less. U.S. Customs and Border Protection claimed in a statement that the frightened girl “provided inconsistent information during her inspection.”

Under a previous president, such an incident might have been written off as a mistake, or at least a rare case of immigration officials gone rogue. But this was no fluke. Since President Donald Trump took office more than two years ago, he and his allies have tried to alter the potency of citizenship itself—diluting it for some, strengthening it for others. They want nothing less than to redefine what it means to be an American citizen.

To many Americans, citizenship is the most valuable thing they possess. It permanently affixes its bearer within the American body politic, guaranteeing them all the rights and liberties protected by the Constitution. To the president, though, it’s just another asset to devalue for short-term political gain, the long-term consequences be damned.

In the closing weeks of last year’s midterm elections, Trump openly toyed with the idea of revoking birthright citizenship by executive order—an unconstitutional act that sought to hand him the power to determine who is and isn’t an American citizen. But that is the closest he’s come to pushing a policy that would change the terms of American citizenship. His actual efforts are more subtle than that.

Trump’s most visible attack on American citizenship is how he denigrates it in public remarks, especially when it comes to his political opponents. Earlier this month, he wrote on Twitter that four women lawmakers of color should “go back and help fix the totally broken and crime infested places from which they came.” Three of the women were born in the United States; the fourth, Minnesota Representative Ilhan Omar, is a naturalized citizen who left Somalia as a refugee decades ago.