The US Department of Homeland Security has amended its rules to require immigrants to disclose their social media accounts. The agency will now collect information including “social media handles, aliases, associated identifiable information, and search results” on immigrants, including permanent residents and naturalized citizens.

Similar rules were first considered last year. The DHS finalized its plans last week, though they weren’t publicized until last night when they were reported by BuzzFeed News. The changes go into effect on October 18th.

It’s not clear whether social media screenings actually help

The initiative originally came in response to the San Bernardino attack in 2015. At the time, reports spread that one of the attackers had expressed extremist views on social media, leading to calls for deeper security screenings.

However, that wasn’t quite what happened. While the attackers had communicated over social media, then-FBI director James Comey clarified that it was done through “direct, private messages,” which government agencies would not have been able to see. “We have found no evidence of posting on social media ... reflecting their commitment to jihad or to martyrdom,” Comey said.

As BuzzFeed points out, there isn’t any proof yet that social media screenings are effective. In February, the DHS’s Inspector General’s office said that pilot tests of social media screenings “lack criteria for measuring performance to ensure they meet their objectives.” Without such information, the IG’s office said, the tests “provide limited information for planning and implementing an effective, department-wide future social media screening program.” That seems to be what’s happening now.