According to the Chosun Ilbo, one drone crashed on Baeknyeong Island on Monday, not long after the North and South engaged in artillery fire. The others had crashed in Paju, Gyeonggi Province on March 24, the paper reported.
While the South Korean government hasn't formally accused anyone of being behind the drones yet, there's one obvious suspect: North Korea.
Why? First, the North is the state with the most reason to attempt to spy on the South. Secondly, Yonhap News has reported that the drones flight route appeared to suggest they began their journey in the North. The drones also bear a strong resemblance to other military drones paraded by the North Korean air force in Pyongyang recently (though those larger drones were much larger and reportedly designed for "suicide" attacks). Finally, a South Korean official has told reporters that the batteries used in the drone had North Korean-style writing on them.
Experts consulted about the drone seem unanimous in pointing out that it's an extremely unsophisticated affair. "It is like a toy," Kim Hyoung-joong, a cyber-defense professor at Korea University in Seoul, told Reuters, while another expert described it to Yonhap as like a "model airplane."
That doesn't mean it's not worrying. According to Korea JoongAng Daily, one of the drones that crashed on March 24 had managed to take photos of landmarks in central Seoul, including the president's official residence, the Blue House and the Gyeongbok Palace, apparently undetected before it crashed. It's not clear if other drones have done the same.