Trump administration has allegedly started administering polygraph tests to government officials in order to identify those leaking information regarding immigration raids to the press. CBS News reports that the Department of Homeland Security (DHS) has been giving these lie-detector tests for more than three weeks, but the number of officials tested is not known.

This comes after the DHS on March 7 announced that it had identified “criminal leakers” in the department and was ready to refer them to the Department of Justice. Homeland Security Secretary Kristi Noem said that they may be charged with felonies and face up to ten years in federal prison.

Polygraph exams were initially implemented by the DHS on February 18 as a measure to stop leaks. The department also cautioned against video recording and broadcasting immigration raids, stressing that enforcement efforts were not intended to be entertainment but instead a question of national security and legal responsibility.

Since January, the Trump administration has stepped up the crackdown on illegal immigration, removing more than 50,000 unauthorized immigrants. The emphasis has been on persons with criminal records, including violent offenders and narcotics traffickers. Immigration and Customs Enforcement (ICE), which functions under DHS, has conducted nationwide raids in scale, arresting thousands of people.

Noem publicly announced last week that over 20,000 illegal immigrants were apprehended in February alone. In the meantime, Trump’s trade practices have also impacted border control measures as Mexico deployed 10,000 soldiers to stem unlawful entries and fentanyl smuggling. Canada also implemented stronger controls against the production and trafficking of fentanyl. The efforts of the administration demonstrate an overarching strategy to strengthen border control and dampen unauthorized migration.