(Pyongyang Press Corps Pool via AP, file) In this Sept. 19, 2018, file photo, Kim Yo Jong, right, sister of North Korean leader Kim Jong Un, helps Kim sign joint statement following the summit with South Korean President Moon Jae-in at the Paekhwawon State Guesthouse in Pyongyang, North Korea. Kim's prolonged public absence has led to rumors of ill health and worries about how it could influence the future of what one analyst calls Northeast Asia's "Achilles' heel," a reference to the North's belligerence and unpredictable nature.