Over the weekend, the US Department of Homeland Security’s X account appeared to reference an antisemitic dog whistle. And it wasn’t the first time that happened this summer. “Which way, American man?” the department’s official page posted Sunday, over a political cartoon from 1936 called “Uncle Sam at the Crossroads.” The post, a recruitment ad for Immigration and Customs Enforcement, alluded to the phrase “Which way, Western man?” — the title of a 1978 book steeped in antisemitic conspiracy theories and explicit threats against Jews. As a social media meme, the phrase has been used to ridicule the “woke,” feminism...