The growing availability of small, inexpensive UAVs that can (and are) used by criminals and Islamic terrorists has led to the development of several Anti-UAV Defense Systems (AUDS). These systems consist of multiple sensors (visual, heat, radar) to detect the small UAVs and a focused radio signal jammer to cut the UAV off from its controller and prevent (in most cases) the UAV from completing its mission. The detection range of AUDS is usually 10 kilometers or more and jamming range varies from a few kilometers to about eight.
AUDS can be defeated. For example a user can send a small UAV off on a pre-programmed mission. This can be to take photos or deliver a small explosive. No one has tried, at least successfully, using armed micro-UAVs yet but North Korea has been caught using small recon UAVs flying under automatic control.
If these UAVs are still detected they have to be destroyed via ground or air-to-air fire. This the South Koreans and Israelis have had to do several times. The Israelis were dealing with Palestinian Islamic terrorist groups using small UAVs, often Iranian models. South Korea and Israel has responded by adding more sensor systems, especially new radars that can detect the smallest UAVs moving at any speed and altitude. An American firm has demonstrated a high-powered laser that can take down small UAVs several kilometers away.
North Korea had been interested in UAVs since the 1970s but had never bought or built a lot of them. In the late 1980s North Korea acquired some of China’s first generation UAVs (ASN-104s). These were 140 kg (304 pound) aircraft with a 30 kg (66 pound) payload and endurance of two hours. Very crude by today’s standards but it took real time video and higher resolution still photos. In the 1990s the North Koreans produced some ASN-104s, apparently by just copying the Chinese ones they had. In the 1990s North Korea got some Russian DR-3 jet powered UAVs. These were faster but less useful than the ASN-104s. Attempts to use the DR-3 as the basis for a cruise missile design failed. In the 1990s North Korea also got some Russian Pchela-1T UAVs. These were very similar to the ASN-104s and that means not very useful at all. The Chinese and Russians used these first generation UAVs mainly for correcting artillery fire and this is what North Korea was seen doing with them, particularly North Korean coastal artillery.
In 2014 South Korea was alarmed to discover three North Korean UAVs that had crashed in South Korea. It was soon discovered that North Korea was using modified versions of the commercial Chinese SKY-09P UAV. North Korea gave the SKY-09Ps a new paint job (to make it harder to spot), a muffler (to make it less detectable) and installed a different camera. The SKY-09P was used via its robotic mode, where the SKY-09P flew to pre-programmed GPS coordinates, taking digital photos over selected areas and returned with those photos stored on a memory card. The SKY-09Ps found in South Korea had GPS coordinates in their guidance system showing they originated and were to return to a location in North Korea. The memory cards showed pictures of South Korean government (mainly military) facilities.
Thus the most successful UAV the North Koreans ever used turned out to be a Chinese commercial model, the SKY-09P. This is a 12 kg (26 pound) delta wing aircraft with a wingspan of 1.92 meters (6.25 feet), propeller in the front and a payload of three kg (6.6 pounds). It is launched via a catapult and lands via a parachute. Endurance is 90 minutes and cruising speed is 90 kilometers an hour. When controlled from the ground it can go no farther than 40 kilometers from the controller. But when placed on automatic it can go about 60 kilometers into South Korea and return with photos. These things cost the North Koreans a few thousand dollars each. While South Korea says they detected two of the three crashed North Korea UAVs no other details were provided. The Chinese manufacturer denied selling anything to North Korea, but the North Koreans typically use a third party for purchases like this.