Kim Yo Jong, the younger sister of North Korean leader Kim Jong Un, has long been confined to her brother’s not-insignificant shadow. But, in recent weeks, Yo Jong has shown that she is far more than just her brother’s ashtray-carrying secretary. She has launched a series of fiery rhetorical attacks against South Korea, accusing “South Korean scum” of “polluting the inviolable territory” of the North by distributing “political and conspiratorial” material.