Why the Pittsburgh shooter raged about immigration before attacking a synagogue

On Saturday, a shooter opened fire inside a synagogue in the heart of a heavily Jewish neighborhood in Pittsburgh. The attack occurred during Shabbat services and during a bris, a celebration of a newborn life.

Immediately before the massacre, the alleged killer tweeted about HIAS, an organization once known as the Hebrew Sheltering and Immigrant Aid Society that dates back to the late 19th century. "HIAS likes to bring invaders that kill our people, " he wrote. It doesn't take a deep understanding of American anti-Semitism to know that to him, "our people" did not include Jewish Americans, even though Jews have lived in America since before the founding of the United States and the congregation he attacked has been convening to pray since the Civil War.

Why, then, did this white-nationalist xenophobe gun down local Jews to protest HIAS? The massacre reflects a stark reality with deep roots in American history: Anti-Semitism, nativism and anti-immigrant sentiments have long been inextricably intertwined.

The anti-Semitism that drove the immigration policy of the early 20th century never faded from American life. Nor did its connection to anti-immigrant sentiment. And that sentiment is what compelled a shooter ranting about HIAS to massacre Jews who were part of a congregation that dates to the 1800s and is located in a city where HIAS has no offices or presence.