The Trump administration has directed immigration officials to review the cases of refugees admitted under former President Joe Biden, as part of an unprecedented effort to identify potential reasons that would disqualify them from being able to stay in the U.S., an internal federal government memo obtained by CBS News shows.

The memo, dated Nov. 21 and signed by U.S. Citizenship and Immigration Services Director Joseph Edlow, instructs agency officials to investigate the cases of refugees who entered the U.S. over a four-year period, between Jan. 20, 2021, and Feb. 20, 2025.

Edlow directed USCIS officials to review the cases of all refugees admitted during this time period, and to potentially reinterview them. Those investigations and reinterviews, Edlow wrote, would focus on determining whether those individuals met the definition of a refugee when they entered the U.S. and whether there are any legal barriers that would make them ineligible to become permanent residents of the U.S.

The memo also placed an indefinite hold on all pending applications for green cards (or permanent residency) filed by refugees allowed into the country during the timeframe outlined in the memo. Under U.S. law, refugees are eligible for permanent residency one year after being admitted.

Edlow noted that applicants cannot appeal any denials of their green card cases. If the cases of "principal" refugees -- or the main applicant if they arrived with their family members -- are rejected, their relatives' cases would also be denied, and they would be stripped of their refugee status, according to the memo. Those whose applications are denied can be placed in deportation proceedings.

Refugees have to prove they suffered or fled persecution abroad based on one of five factors: their race, nationality, religion, political opinion or membership in a social group.

Some 233,000 refugees entered the U.S. between February 2021 and January 2025, a period that largely lines up with the Biden administration, according to federal statistics.

The federal government paused the refugee program shortly after President Trump retook office. Officials have made limited exceptions, mostly for Afrikaners, or people in South Africa who are the descendants of European settlers.

Last month, the Trump administration capped refugee admissions for this fiscal year at 7,500, the lowest level in history. Those slots will "primarily be allocated among Afrikaners," who the Trump administration alleges have faced discrimination in South Africa for being White, and "other victims of illegal or unjust discrimination in their respective homelands." The South African government has denied that Afrikaners are being persecuted.

Before the pause, refugees typically spent years in third countries undergoing medical checks, security screenings and interviews prior to being admitted into the U.S.

But in his memo, Edlow said the Trump administration believes the Biden administration "prioritized expediency, quantity, and admissions over quality interviews and detailed screening and vetting."