US Secretary of State Rex Tillerson has ordered a “mandatory social media check” on all visa applicants who have ever visited ISIS-controlled territory, according to diplomatic cables obtained by Reuters. The four memos were sent to American diplomatic missions over the past two weeks, with the most recent issued on March 17th. According to Reuters, they provide details into a revised screening process that President Donald Trump has described as “extreme vetting.”

A memo sent on March 16th rescinds some of the instructions that Tillerson outlined in the previous cables, including an order that would have required visa applicants to hand over all phone numbers, email addresses, and social media accounts that they have used in the past. The secretary of state issued the memo after a Hawaii judge blocked the Trump administration’s revised travel ban on citizens from six predominantly Muslim countries.

In addition to the social media check, the most recent memo calls for consular officials to identify “populations warranting increased scrutiny.” Two former government officials tell Reuters that the social media order could lead to delays in processing visa applications, with one saying that such checks were previously carried out on rare occasions.

Immigration attorney Jay Gairson tells Reuters that consular officials already use more targeted criteria to assess visa applicants for security risks, and that the broader orders could lead to profiling based on religion or nationality. “What this language effectively does is give the consular posts permission to step away from the focused factors they have spent years developing and revising, and instead broaden the search to large groups based on gross factors such as nationality and religion," Gairson said.

Following Trump’s initial travel ban, handed down through executive order in January, it was reported that border agents were asking some travelers to provide access to their social media accounts. US Customs and Border Patrol introduced an optional social media account field on visa waiver forms in December, though there have been complaints filed over cases where agents aggressively sought access to travelers’ phones and social media accounts, as The Verge reported in January.

A social media screening pilot program launched by the Department of Homeland Security under the Obama administration failed to measure the effectiveness of such screens, according to a recent report from the agency’s inspector general.