SEOUL—North Korea leader Kim Jong Un’s kid sister Kim Yo Jong is brandishing the threat of germ warfare in retaliation for balloon launches from South Korea that she blames for spreading COVID-19 in the North.

Kim Yo Jong, in a speech carried on North Korean state TV, said, after having considered “various counteraction plans, our countermeasure must be a deadly retaliatory one.”                                                                                 Her remark suggests she and her brother are not only fed up with defectors from North Korea launching balloons from the South carrying anti-North propaganda but are determined to respond in kind. The logical answer to her claim that the South is sending the dread disease to the North, it’s feared, would be for North Korea to inflict diseases on the South.                                                                                                                       “If the enemy persists in such dangerous deeds as fomenting the inroads of virus into our Republic,” Pyongyang’s Korea Central News Agency quotes her as saying, “we will respond to it by not only exterminating the virus but also wiping out the south (sic) Korean authorities.”                                                                               The fact that North Korean TV showed Kim Yo Jong making a speech was a sure sign of the seriousness of the message. Previously, when expressing her brother’s views more boldly than he might want to do publicly, she was quoted in reports, not live on TV.                                                                                                                       Defector Rains COVID Aid Down on North Korea Via Balloons                                                                              Kim Yo Jong, whose only title is vice department director of the Central Committee of the Workers' Party, ranks at or near the top of the regime’s hierarchy. Were the hefty Kim Jong Un, 38, whose health is always open to question, to die or be incapacitated, 34-year-old Yo Jong would inevitably be a leading possibility to succeed him.                                                                                                                                                                           None of which means she’s about to take over soon or has the power to do anything Kim Jong Un hasn’t ordered. She spoke before a meeting convened by the party’s central committee at which he “solemnly declared the victory