Something unexpected is happening at U.S. military bases hosting Afghan evacuees: Many hundreds of them are simply leaving before receiving U.S. resettlement services, two sources familiar with the data told Reuters.

The number of “independent departures,” which top 700 and could be higher, has not been previously reported. But the phenomenon is raising alarms among immigration advocates concerned about the risks to Afghans who give up on what is now an open-ended, complex, and completely voluntary resettlement process.

In the speed and chaos of the U.S. withdrawal from Afghanistan in August following 20 years of war, many evacuees were brought into the United States under a temporary status of “humanitarian parole.” Once transferred to U.S. military bases, refugee resettlement groups and U.S. officials have been trying to connect people with services for a smooth transition to the United States.

In a statement, a U.S. Department of Homeland Security (DHS) spokesperson declined to comment on the figures provided to Reuters by sources but said people who had left the bases “generally” had ties to the United States, like family members of friends, and resources to support themselves.... Read More: Newsmax