For the past few years, a specialized team of about half a dozen employees within Airbnb has been assigned an urgent task: preventing white nationalists and other potentially dangerous fringe groups from renting homes on the site.

Working inside the company’s trust and safety unit, the employees comb through Facebook, Twitter and far-right online forums and track where rallies are planned. Often the team creates dummy accounts on Facebook, known as “sock puppet” accounts, to monitor customers publicly embracing propaganda that could encourage violence. Airbnb has suspended more than 100 accounts of individuals affiliated with such groups, according to one employee.

Airbnb’s use of social media to trace guests, which hasn’t been previously reported, has played an important role in its attempts to stop violent hate groups from booking homes, one current and three former employees involved in safety work said. The efforts, which began in the run-up to the far-right rally in Charlottesville, Va., in 2017, have taken on new urgency after an assortment of far-right and hate groups participated in the Jan. 6 attack on the U.S. Capitol.