The number of anti-UAV weapons showing up indicates that the countries with larger defense budgets see a need for this sort of thing and are willing to pay for a solution. That need has been created by the growing availability of small, inexpensive UAVs that can (and are) used by criminals and Islamic terrorists. These more sophisticated AUDs (Anti UAV Defense) are safer (for nearby civilians) to use because they rely on lasers or electronic signals to destroy or disable UAVs. For example the CLWS (Compact Laser Weapon System) is a laser weapon light enough to mount on helicopters or hummers and can destroy small UAVs up to 2,000 meters away while it can disable or destroy the sensors (vidcams) on a UAV up to 7,000 meters away. The CLWS fire control system will automatically track and keep the laser firing on a selected target. It can take up to 15 seconds of laser fire to bring down a UAV or destroy its camera. Another example is an even more portable system that can be carried and operated by one person. This is DroneDefender system, which is a 6.8 kg (15 pound) electronic rifle that can disrupt control signals for a small UAV. Range is only a few hundred meters so DroneDefender would be most useful to police.
There is also a high-end system similar to DroneDefender that can use data from multiple sensors (visual, heat, radar) to detect the small UAVs and then use 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 this 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. The downside of using missiles to machine-guns to take down UAVs is that those bullets and missiles eventually return to earth and often kill or injure people (usually civilians) on the ground.