A few years ago, Facebook, Twitter and YouTube found themselves under withering criticism from governments around the world who said their platforms had become a haven for bad actors seeking to spread damaging propaganda. The problem then wasn't Russian election meddling. It was Islamic State militants. To some security experts, the resistance companies had to using the hashing technology to catch terrorism posts is echoed in today’s reluctance to treat foreign interference as a similar issue. “This is very much the same issue,” said Hany Farid, a computer science professor at Dartmouth College who helped develop the shared hashing technology when it was put to use to combat child pornography and serves as an adviser to the Counter Extremism Project, a non-profit that has pressured technology companies to curtail terrorist material.