South Korea says North Korea has fired artillery near their sea boundary for a third straight day

South Korea's military strongly urges North Korea to halt provocative acts as it fires artillery shells near the sea boundary for a third straight day. North Korea's influential sister, Kim Yo Jong, mocks South Korea's ability to detect weapons launches and denies the claim of firing artillery shells into the sea. South Korea's military dismisses her statement as 'low-level psychological warfare' and warns of a stern response to any provocations. Both Koreas established maritime buffer zones.