Trump administration directing ICE to track down unaccompanied minors: Source

More than 600,000 migrant children have crossed the southern border since 2019.

President Donald Trump's administration is directing immigration agents to track down unaccompanied migrant children in the U.S., a source familiar with the plans told ABC News.

An internal document from Immigration and Customs and Enforcement (ICE), headlined the "Unaccompanied Alien Children Joint Initiative Field Implementation," said the initiative claims to prevent children from being human trafficked or other types of exploitation.

There are more than 600,000 migrant children who have crossed the U.S.-Mexico border without a legal guardian or parent since 2019, according to government data.

The initiative, according to the source familiar, claims to ensure migrant children are not victims of human trafficking or victims of other forms of exploitation. The plan, which lays out four phases of implementation, said minors would be served a notice to appear in immigration court or deported -- if deportation orders were pending against them.

ICE collected data on unaccompanied minors and sorted them into three groups: "flight risk," "public safety" and "border security." Agents were told to prioritize "flight risk" minors, including those who have received orders of deportation for missing court hearings, the source said of the internal document.

The move from the Trump administration comes after Republicans claimed last year that the Biden administration "lost 300,000" migrant children -- a figure experts and advocates say lacks context.

The claims come from a DHS internal watchdog report last year that found that ICE had not served notices to appear to more than 291,000 unaccompanied migrant children. The internal watchdog warned that in the past five years, more than 32,000 unaccompanied migrant children failed to appear for their immigration court hearings, and ICE was "not able to account" for all of their locations.

"The unique needs of children require the administration to ensure a level of care that takes into account their vulnerability while it determines whether they need long-term protection in the United States," Wendy Young, the President of Kids in Need of Defense said in a statement to ABC News.

"To be successful in its goals, the government must partner with legal service providers and the vast network of private sector pro bono partners who provide millions of dollars in free legal services to ensure children understand the process and can share their reasons for seeking safety in the United States. Then the government can decide with confidence who needs protection and who can safely return to their country of origin," Young added.

Reuters first reported the contents of the internal document from ICE.