The Trump administration is subjecting broad categories of immigrants applying for legal immigration benefits to enhanced security checks, and is pausing some cases while the changes are implemented, according to internal government documents obtained by CBS News.

Last week, U.S. Citizenship and Immigration Services distributed internal guidance instructing its officers to resubmit pending applications for different immigration benefits, including asylum, green cards and U.S. citizenship, to enhanced FBI background checks, the documents show.

Officers were directed to refrain from approving any pending cases that have not undergone the expanded background checks.

USCIS has long used FBI databases to vet immigration applications for potential national security or public safety concerns. But the documents indicate the enhanced security screenings were prompted by the FBI's decision to grant USCIS greater access to its criminal history database, as part of an executive order by President Trump in February.

That order directed the Justice Department, which oversees the FBI, to provide USCIS access to its criminal history database "to the maximum extent permitted by law" to identify criminal actors.

"Such criminal actors may include foreign nationals with criminal histories who have entered or remained in the United States in violation of the immigration laws of the United States or who otherwise seek to violate the criminal laws of the United States," the president said in his order.

The enhanced checks will affect pending applications for benefits for which applicants have to submit fingerprints, such as requests for green cards (permanent U.S. residency) and naturalization, according to the internal guidance. It will also apply to sponsorship petitions filed on behalf of relatives or fiancees of U.S. citizens or green card holders.

USCIS officers were directed to re-submit fingerprint-based screenings if the FBI information for the cases in question was received before April 27. Officers were told the resubmissions are not necessary if they intend to deny an application.

In a statement to CBS News, USCIS spokesperson Zach Kahler confirmed the agency had "implemented new security checks to strengthen the vetting and screening of applicants through expanded access to federal criminal databases."

"Processing is ongoing as we apply these enhanced background check requirements. Any delay in decision issuance should be brief and resolved shortly," Kahler said. "USCIS will always prioritize the safety of the American people." 

The expanded security checks represent the latest front in the Trump administration's campaign to aggressively vet people applying for immigration benefits and tighten access to the U.S. immigration system. 

Since Trump returned to the White House, USCIS has rolled out multiple policies to more heavily scrutinize immigration applications, including for evidence on social media that applicants have engaged in "anti-American" views or activities.

The second Trump administration has also slowed or completely halted processing of many immigration cases, including by enacting a pause on all asylum cases overseen by USCIS and freezing all legal immigration requests filed by nationals of 39 countries listed on a presidential proclamation, known as the "travel ban," that imposed immigration restrictions on national security grounds.

The USCIS asylum pause was scaled back last month, as first reported by CBS News, but remains in place for immigrants from the 39 countries on the travel ban.