President Donald Trump signed an order Thursday that would prevent children of mothers who travel to the United States to give birth from automatically becoming American citizens. The move is his latest attempt to restrict birthright citizenship, after an earlier effort was rejected by the U.S. Supreme Court, which ruled that such citizenship is protected by the U.S. Constitution. The order specifically targets "birth tourism," a practice in which expectant mothers enter the country to deliver babies and secure U.S. citizenship for them. The Supreme Court's previous ruling stated that the Constitution grants citizenship to anyone born on American soil.