Washington (AP) — Pushing forward with its mass deportation agenda, President Donald Trump’s administration said Monday that it would pay $1,000 to immigrants who are in the United States illegally and return to their home country voluntarily.

The Department of Homeland Security said in a news release that it would also pay for travel assistance — and that people who use an app called CBP Home to tell the government they plan to return home will be “deprioritized” for detention and removal by immigration enforcement.

“If you are here illegally, self-deportation is the best, safest and most cost-effective way to leave the United States to avoid arrest,” Secretary Kristi Noem said. “DHS is now offering illegal aliens financial travel assistance and a stipend to return to their home country through the CBP Home App.”

The department said it had already paid for a plane ticket for one migrant to return home to Honduras from Chicago and said more tickets have been booked for this week and next.

It’s a major part of Trump’s administration

Trump made immigration enforcement and the mass deportation of immigrants in the United States illegally a centerpiece of his campaign, and he is following through during the first months of his administration. But it is a costly, resourceintensive endeavor.

While the Republican administration is asking Congress for a massive increase in resources for the Immigration and Customs Enforcement department responsible for removing people from the country, it’s also pushing people in the country illegally to “self-deport.”

It has coupled this self-deportation push with television ads threatening action against people in the U.S. illegally and social media images showing immigration enforcement arrests and migrants being sent to a prison in El Salvador.

The Trump administration has often portrayed self-deportation as a way for migrants to preserve their ability to return to the United States someday, and the president himself suggested it on Monday while speaking to reporters at the White House. He said immigrants who “self-deport” and leave the U.S. might have a chance to return legally eventually “if they’re good people” and “love our country.”

“And if they aren’t, they won’t,” Trump said.

But Aaron Reichlen-Melnick, a senior fellow at the American Immigration Council, which advocates for immigrants, said there’s a lot for migrants to be cautious about in the latest offer from Homeland Security.

He said it’s often worse for people to leave the country and not fight their case in immigration court, especially if they’re already in removal proceedings. He said if migrants are in removal proceedings and don’t show up in court they can automatically get a deportation order and leaving the country usually counts as abandoning many applications for relief including asylum applications.

This has been tried before 

Other countries have tried various iterations of paying migrants to return home.

There’s a reason it’s attractive to governments wanting to encourage migrants to go. It costs less to buy someone a plane ticket and some incentive money than it does to pay to find them, detain them if necessary, wait for the courts to rule on their case and then send them home.

The Department of Homeland Security said that it costs $17,121 to arrest, detain and remove someone in the U.S. illegally.

Voluntary returns also don’t require extensive government-to-government negotiations to get a country to take back its citizens, which can be a major benefit. There are a number of countries that either don’t take back their own citizens who are being returned by U.S. immigration enforcement officials or make that process challenging.

A 2011 study by the Migration Policy Institute and the European University Institute found that there were about 128 programs — often referred to as pay-togo programs — around the world.

But the study found that, with a few exceptions such as one program to return people in the 1990s from Germany to Bosnia, these voluntary return programs generally failed at encouraging large numbers of people to go home.