German policy of clearly marking and accurately recording the locations of minefields. However, incidents involving accidental explosions of mines in North Africa, the former Warsaw Pact countries, France, and Germany still occur sporadically. North Africa and Eastern Europe have a particularly large amount of uncleared World War II-era minefields, lost in the desert sands or forgotten by authorities. In Libya, for example, the Red Cross estimates that over 27% of farmland is unusable due to World War II minefields. While German documentation says the S-mine had an effective lifespan of two to seven years once planted, the explosive charge could still operate in mines to this day. Characteristics The German S-mine was a steel cylinder approximately tall without its sensor and around in diameter. A steel rod protruding from the mine's top held the main fuse, where its trigger or sensor was attached. The SMi-35 had a central fuse, while the SMi-44 had an offset fuse. It weighed approximately , with the weight depending on whether it was loaded with the lighter powdered or the heavier poured TNT. The main charge of the mine used TNT as its explosive; the propelling charge was black powder. The standard pressure sensor used a percussion cap to ignite it. The main fuse was designed to delay the firing of the propelling charge for approximately four seconds after the mine was triggered. The explosion of the propelling charge sent the mine upwards into the air and activated three short-delay pellets between the propellant charge and the three detonators. These short-delay pellets delayed the mine's detonation long enough for it to reach an appropriate height before exploding. The standard pressure sensor was designed to activate if depressed by a force equivalent to a weight of roughly or greater. This ensured the mine was not detonated by wildlife or natural impact of blowing leaves, branches, or other normally occurring phenomena. Usage The S-mine was normally triggered by a three-pronged pressure fuse. It could also be modified to be triggered by a tripwire. A special tripwire adapter was provided by the German army. The steel tube that held the fuse was threaded to accept any standard German ignition or trigger, allowing the sensor to be removed and the mine to be deliberately triggered by a human operator. When triggered, the mine functioned in three stages (see diagram). First, the mine was fired upwards by a small propellant