At the time of Cold War, both sides employed the use of bugs (remote listening devices) in order to spy the other side by listening in on a room, a building, or, in the case of East Berlin, an entire city. But in case of America’s war with Afghanistan, the US forces may perform the biggest bugging operation till now by planting sensors all over the country. These bugs can feed the US forces for the next two decades. It’s a rough estimation that entire Afghanistan would be bugged!
The small devices as big as a human palm aren’t actually listening devices, rather they would detect nearby movements and will report it to the US intelligence. It would help the US officers know whenever a remote mountain or a smuggling trail is used by someone. The sensors camouflage with the environment. Some sensors could be buried inside soil while others could be disguised as rocks and other geographical things. They would cover whole Afghanistan and would remain functional for 20 years.
Such unattended ground sensors (UGSs) were earlier used in Vietnam. However these new UGSs are better than those sensors used earlier. These sensors use lesser power and their batteries could be charged from solar power as well. This would help them to remain functional for longer periods as long as 20 years as claimed by the manufacturing company, Lockheed Martin.
These sensors would have audio, seismic, or even phased-array radar instruments that can keep an eye on whole countryside in a mesh network of surveillance. Whenever a sensor detects some activity, it sends its location to surveillance airships above telling them to get a closer look.
Such UGSs are already being used around bases in Afghanistan and also at the US-Mexico Border. But bugging complete Afghanistan is a very huge process. Such a sensor would cost around $1000 per unit which is a very nominal cost for such an uninterrupted intel.