"It’s the unmarked cars,” a friend who grew up under an Argentine dictatorship said. He had watched the video of Columbia graduate student Mahmoud Khalil’s abduction. In the video, which Khalil’s wife recorded, she asks for the names of the men in plainclothes who handcuffed her husband.

"We don’t give our name,” one responds. "Can you please specify what agency is taking him?” she pleads. No response. We know now that Khalil was detained by Immigration and Customs Enforcement, an agency of the Department of Homeland Security.

Those of us who have lived in countries terrorized by a secret police force can’t shake a feeling of dreadful familiarity. "I never realized until this moment how much fear I carried with me from my childhood in communist Romania,” another friend, literary scholar Marianne Hirsch, told me. "Arrests were arbitrary and every time the doorbell rang, I started to shiver.”