Some migrants who were arrested during Trump's immigration crackdown have been released back into the U.S.

 Due to space limitations and court orders, ICE has been releasing migrants onto monitoring programs after their arrests.

Immigration and Customs Enforcement agents during a multi-agency targeted enforcement operation in Chicago on Jan. 26.

Feb. 3, 2025, 6:00 PM GMT+6

The Trump administration made a point of publicizing the arrests of over 8,000 immigrants by federal agents since Inauguration Day, promising that these individuals would be part of a historic mass deportation effort. However, NBC News has learned that some of those arrested have already been released back into the U.S. through a monitoring program, according to five sources familiar with the operations.

Since taking office, President Donald Trump and his supporters have highlighted immigration crackdowns in cities like Chicago and New York, where federal agencies have stepped up arrests. However, making more arrests for immigration violations requires space to hold those detained. With overcrowding in Immigration and Customs Enforcement (ICE) detention centers and federal court orders prohibiting indefinite detention, the agency has had to release some detainees rather than hold them until deportation.

While ICE publishes daily arrest statistics on X, it does not disclose how many of those arrested are released, remain in custody, or have been deported.

An ICE spokesperson confirmed to NBC News that federal court rulings prevent ICE from holding detainees indefinitely, especially if their countries refuse to accept their return, which can lead to their release.

“The agency’s federal law enforcement officers do everything they can to keep our communities safe,” the spokesperson said. “In some cases, ICE is required to release certain arrested aliens from custody.”

Those released are placed on a monitoring program called Alternatives to Detention, which has been used for over a decade to track migrants through the immigration system. ICE monitors them through ankle bracelets, wristbands, or telephonic check-ins, according to the five sources.

As he did during his first term, Trump vowed to end “catch-and-release” policies, which allow migrants apprehended at the southern border to be released into the U.S. while their immigration cases are pending. While the "catch and release" policy appears to be suspended at the southern border, where fewer migrants are being processed for asylum, ICE's detention capacity remains limited to just 41,500 beds nationwide. This has led to the release of some migrants detained in the interior of the country.

In December, Fox News reported that the incoming Trump administration was aware of the detention capacity issues and was considering expanding the ankle monitor program.

ICE prioritizes detaining immigrants who pose a public safety threat and gives officers discretion to release those without serious criminal convictions. There is no indication that the Trump administration has released anyone with a serious criminal record.

When deciding whether to detain or release someone, ICE also factors in whether the immigrant comes from a country that refuses to take them back. For instance, hundreds of thousands of Venezuelans in the U.S. couldn’t be deported and were considered for release if they were not seen as public safety risks.

On Saturday, Trump announced that Venezuela had agreed to accept the return of its nationals who had emigrated to the U.S.

Other detainees may also be released for medical reasons or if they are the sole caregivers for children, according to three sources familiar with the decisions.