In Hungary, hundreds of migrants surrounded by armed police officers were tricked into boarding a train with promises of freedom, only to be taken to a “reception” camp. In the Czech Republic, the police hustled more than 200 migrants off a train and wrote identification numbers on their hands with indelible markers, stopping only when someone pointed out that this was more than a little like the tattoos the Nazis put on concentration camp inmates.

Razor-wire fences rise along national borders in Greece, Bulgaria, Hungary and France. Many political leaders stoke rising nationalism by portraying the migrants as dangerous outsiders whose foreign cultures and Muslim religion could overwhelm cherished traditional ways.

“It was horrifying when I saw those images of police putting numbers on people’s arms,” said Robert Frolich, the chief rabbi of Hungary. “It reminded me of Auschwitz. And then putting people on a train with armed guards to take them to a camp where they are closed in? Of course there are echoes of the Holocaust.”