An U.S. Department of Defense official said: "China has installed jammer equipment at two fortification posts on the Spratly Islands to block communications and radar systems, which is an important step in its gradual militarization." The official also said in Syria Similar uav jammers devices have also been found on the battlefield. Such devices were developed by the Russian military and are very complex, even for certain encrypted signals and anti-jamming devices. The drones affected so far have been smaller reconnaissance aircraft, which are different from large "predators" and "harvesters", which usually operate in combat environments and can be armed.
NBC News quoted four sources inside the Pentagon as saying that broadcasts of GPS signal jammer began a few weeks ago. It began in the rebel-controlled Guta area, allegedly shortly after a chemical attack by the Syrian regime. According to reports, the Russian army is worried that the U.S. military will retaliate and use chemical weapons and drones to prevent the U.S. military from collecting information. At present, drone jammers are not only used in military battlefields, but also in civilian and commercial fields.