The U.S. traditionally pushed other countries to crack down on human traffickers and toughen their laws on trafficking. But in 2018, only five countries changed their laws, down from 25 in 2016. Many more tough laws are still needed.

The administration has also made no attempt to address underlying causes of trafficking — such as child poverty. America’s foster care system, for example, is dysfunctional and amounts to a pipeline for traffickers. The National Academies of Sciences, Engineering and Medicine last year offered an important road map to cut American child poverty by half — a step that would reduce trafficking — but the administration has ignored it.

“We are losing the ‘war on trafficking,’ mostly because we have made this all about prosecutions,” Vandenberg said. “We are doing almost no prevention.”

Rachel Lloyd, who was trafficked into the sex trade as a teenager, now runs an excellent program in New York City called the Girls Educational and Mentoring Service, or GEMS, which helps girls who have been trafficked. Lloyd said that when she realized that the administration was only engaged in a P.R. effort, she turned down a position on an administration advisory panel and also declined a $10,000 donation from Ivanka Trump for GEMS.

“Why would we give them cover and validation?” asked Lloyd, whose memoir, “Girls Like Us,” is one of the best books on trafficking.

Human trafficking is one of the pre-eminent moral challenges of our time. The International Labor Organization estimates that worldwide, some 10 million children exist in forms of modern slavery. In Cambodia, I once saw terrified young girls being sold for their virginity; in Pakistan, I saw a brothel owner determined to kill a girl who had escaped.

Trump’s exploitation of trafficking victims for his own purposes is particularly sad because this is a rare issue where Democrats and Republicans have worked productively together: Evangelical Christians and liberal feminists both have done heroic work for 20 years. Representative Chris Smith, a Republican from New Jersey, has done outstanding work on this issue, as has Gloria Steinem.