In less than 250 days, an estimated 1.6 million illegal immigrants voluntarily self-deported, while 400,000 were removed by federal law enforcement, the DHS said, describing the situation as a “new milestone.”

In May, Trump signed an executive order establishing the first-ever self-deportation program that incentivizes illegal migrants to voluntarily leave the country on a free flight and with a cash bonus.

Homeland Security said that migrants were being offered a $1,000 stipend each to leave. The department said it is 70% cheaper for American taxpayers, as it currently costs DHS, on average, over $17,000 to arrest, detain and deport someone.

In June, the State Department moved $250 million to DHS for voluntary deportations.

A migrant pulls his suitcase through Logan International Airport’s Terminal E before boarding a flight home. (Jessica Rinaldi/The Boston Globe via Getty Images)

Shaina Aber, the executive director of the Acacia Center for Justice, a nonprofit that provides legal defense to immigrants, said in a statement that the $2,500 stipend undermines due process and may expose children to renewed trafficking cycles.

She said some of these children were trafficked into the U.S., often by cartels or smugglers, and if they are sent back without safeguards, they could fall back into the hands of the same traffickers.

“DHS’s message is confusing and seems to fly in the face of established laws and protocols that Congress passed to protect children from cyclical trafficking risks,” Aber said. 

The Associated Press contributed to this report.