At the request of the U.S. Congress, the Department of Homeland Security is building more advanced tools to scan the social media feeds of visa and asylum applicants, as well as vacationing visitors, in hopes of being able to identify potential terrorist threats before they are allowed to enter the country, reports the New York Times .

Both Republican and Democratic lawmakers have urged the rollout of more advanced tools. On December 22, Democrats sent a letter to DHS Secretary Jeh Johnson urging the agency to begin reviewing an applicant’s social media accounts “immediately,” reports the Times. Republican Senators including John McCain of Arizona have introduced bills that would require the Department of Homeland Security to screen the social media activity of all refugees and visitors wanting to enter the country.

The urging from lawmakers comes as law enforcement and government officials are increasingly becoming concerned about how adept terrorist organizations have become at using Facebook and Twitter to promote their agendas.

The Department of Homeland Security revealed that it already has a list of almost three dozen situations in which it examines the social media accounts of visa and asylum applicants, but says this examination of an applicant’s account isn’t constant. The Times says that the DHS set up a task force last year to explore ways to incorporate the screening of social media accounts into the vetting process and that the department currently has four pilot projects running.

The United States Citizenship and Immigration Services, which is a sub-department of the Department of Homeland Security, already uses social media screening for vetting some Syrian refugees, but only when a refugee has be identified in another security database as a potential threat or when an immigration officer manually raises an issue after interviewing the applicant, notes the Times. In those instances the CIS uses software to scour a refugee’s social media accounts but there is also a lot of manual screening done by human analysts. Currently the CIS also says it has no way to view direct messages sent on via such platforms.

The DHS, at the urging of lawmakers, is hoping to change all that. At the end of the month the agency will bring in experts from the technology industry to talk about the tools available to automatically and constantly scan social media postings and messages.

However, many have voiced concern over the Department of Homeland Security’s plans. The Times notes that travel industry officials and immigration rights activists say the new policy and automated software scanning can subject people with legitimate criticisms of America to unwarranted scrutiny.