Department of Homeland Security Secretary Alejandro Mayorkas told reporters that the new policy was based on the reality that the U.S. can’t go after all people in the country without legal status and shouldn’t try because many “have been contributing members of our communities for years.”

Authorities will be directed to focus on noncitizens who have crossed recently, defined as after Nov. 1, 2020, or who determined to be a threat because of national security or “serious criminal activity.” Homeland Security includes U.S. Immigration and Customs Enforcement and the Border Patrol.

Unlike the interim rules, the criminal activity is not limited to the category known in legal terms as an aggravated felony but will depend on the “totality of the facts and circumstances,” Mayorkas said. Anyone would be considered a priority if they are engaged or even suspected of terrorism or espionage, according to the memo. The new rules take effect Nov. 29.