Seoul says military detected five UAVs crossing the border for 1st time in 5 years; one flew as far as the northern part of the capital region; unclear if they were downed

Kim Yo Jong, sister of North Korean leader, warns that sanctions from Seoul and Washington will only 'add fuel' to Pyongyang's 'hostility and anger'

Tensions rise between two Koreas in dispute over propaganda leaflets, with North Korean leader's sister Kim Yo Jong rejecting South's offer to send calming envoys

Incident north of border comes as nuclear diplomacy with US at an impasse; leader's sister, Kim Yo Jong, warned over weekend of building 'collapsing'