In 2020, officers at Facebook and Twitter contacted the Pentagon to raise concerns about the phony accounts they were having to remove, suspicious they were associated with the military. That summer, David Agranovich, Facebook’s director for global threat disruption, spoke to Christopher C. Miller, then assistant director for Special Operations/Low Intensity Conflict, which oversees influence operations policy, warning him that if Facebook could sniff them out, so could U.S. adversaries, several people familiar with the conversation said.