Just as Kristallnacht was a seminal event in Adolf Hitler’s Germany, the recent explosion of antisemitic demonstrations on Ivy League campuses is a tipping point for President Joe Biden’s America. After six months of calls for an immediate ceasefire and additional humanitarian aid to Palestinians, leftist protesters have upped the ante. Pro-Palestinian activists are now openly threatening the physical safety of Jewish students. And in a number of cases, such as that of an anti-Israel activist poking a Yale student in the eye with a Palestinian flag, it has gone well beyond mere threats. These so-called rallies can no longer...