North Korea's state media said Friday that South Korea has sent unmanned drones over Pyongyang three times since last week, calling the move a military provocation and a violation of its sovereignty.South Korea sent unmanned drones over Pyongyang on Oct. 3, as well as on Wednesday and Thursday this week, according to the Korean Central News Agency, distributing what the North calls propaganda leaflets.North Korea has launched thousands of trash balloons since late May in what it has described as a "tit-for-tat" move against anti-Pyongyang leaflets sent across the border by activists and North Korean defectors in South Korea.Source: Yonhap News Agency