A drone that crashed on Baeknyeong Island on March 31 took photos of South Korean military installations on Socheong and Daecheong Islands during its zigzag course.
According to the Defense Ministry on Thursday, the drone was made of foamcore with layers of fiberglass. Another drone that crashed in Paju, Gyeonggi Province on March 24 and took photos of Cheong Wa Dae and nearby areas was made of polycarbonate. Both materials can avoid radar detection.
The Baeknyeong drone had a 4-cylinder gasoline engine. "It seems that the drone crashed when the engine stopped due to lack of fuel, probably because the amount wasn't calculated accurately," a ministry official speculated. "The fuselage was damaged because the parachute didn't open when it fell to the ground."
Marines on Baeknyeong Island were said to have fired Vulcan gunshots at the drone on March 31, but it was apparently flying somewhere else at the time.
The drone was also equipped with a Japanese-made Nikon D-800 DSLR camera, while the Paju drone had a Canon 550D model.
By analyzing the photos in the Nikon, the military concluded that the drone had flown from the North at an altitude of 1.4 km at an average speed of 100 to 120 km/h.
"Some military installations on Socheong and Daecheong Islands were photographed," the official added. "But there were no photos of Baeknyeong Island, where it crashed."
Like the Paju drone, the Baeknyeong drone has no equipment to send photos in real time, so they can be collected only after the drone finishes its mission. But it contained a remote-control sensor and GPS.
Intelligence authorities here believe that North Korea sent the drone to test the South's defense system, not just simply for the purpose of surveillance.
"The drone is equipped with a Japanese-made DSLR camera that is available in the market. The lenses are not high quality and there is no equipment to transmit images," an intelligence official said. Also, the photos taken by the aircraft could just as easily be obtained from Google Earth, he added.
North Korea more likely wanted to check at which speed and altitude the drone would be detected by the South's air search radar, he said, and the camera was only intended to check speed and distance.